mtsA contains an lipoprotein peptidase cleavage site signal seque

mtsA contains an lipoprotein peptidase cleavage site signal sequence as defined by Linton & Higgins [25]. To confirm that MtsA is a lipoprotein, the crude cell lysate of S. iniae HD-1

was mixed with Triton X-114, and the detergent phase was analyzed by western blotting using rabbit anti-MtsA antibodies (Figure 3B). The results showed that MtsA protein was extracted by Triton X-114. Together, the results indicated that MtsA protein is a lipoprotein. Figure 3 Analysis of the lipoprotein sequence patterns of MtsA by ScanProsite and the western blotting. (A) The mtsABC lipoprotein was assessed by ScanProsite. The results showed that amino acid residues D1 to D24 (MFKKISLAFAMLLSIFCITACSSQ) hit G+LPPv2 pattern, AZ 628 supplier and amino acid residues D17 to D21 (CITAC) hit PS51257 pattern. The symbol “”<"" indicates that the pattern

is restricted to the N terminus, and X is any amino acid. (B) Western blotting analysis results of the lipoproteins extracted learn more with Triton X-114. Purification of recombinant MtsA To be able to further characterize MtsA, we first expressed recombinant MtsA consisting of amino acid residues D27 to D310 that lacked the putative signal sequence. Briefly, mtsA gene was cloned and the PCR product was isolated from the plasmid after a double digestion with restriction enzymes BamHI and XhoI, and ligated into the compatible site of pET-32a-c (+) Vector to yield recombinant protein Calpain MtsA. The expressed MtsA had a molecular mass of 49.5-kDa (Figure 4) with a tag from Trx·Tag to EcoR V of pET-32a-c (+), which has a molecular weight of 17.7-kDa. The expression level of MtsA peaked after induction with 1 mM IPTG at 37°C for 4 h. The MtsA protein was purified from E. coli BL21 (DE3) under native condition n the soluble form and immunized the

New Zealand white rabbits. The results showed that the rabbit anti-MtsA antibody titers increased from essentially zero to 1:50,000 after four rounds of immunization (Additional file 1, Table S4). The western blotting analysis was performed to show the specificity of immunized sera against purified MtsA (Figure 4, and Additional file 2, Figure S3-4). Figure 4 SDS-PAGE and western blotting analysis of expressed and purified MtsA. Lanes 1~4, SDS-PAGE showing the purification results of MtsA. The gels were stained with Coomassie brilliant blue. Lane 1, molecular mass marker; lane 2, E. coli with control pet-32a-c (+) vector; lane 3, E. coli lysate containing MtsA (approximately 49.5-kDa); lane 4, purified MtsA (approximately 49.5-kDa). Lanes 5~7, western blotting results of purified MtsA. Lane 5, E. coli with control pet-32a-c (+) vector; lane 6, E. coli lysate containing MtsA (approximately 49.5-kDa); lane 7, purified MtsA (approximately 49.5-kDa).

Note that in the wavelength region from 500 to 580 nm, the absorp

Note that in the wavelength region from 500 to 580 nm, the absorption curve of P3HT/Si NWA (T = 40 and 80 nm) overlaps with that of bare Si NWA. This is due to the fact that the bare Si NWA exhibits the absorptance close to 1 in this wavelength region. Thus, although the absorptivity is increased as the P3HTs are coated on the surface of NWA, the absorption curves do not exhibit obvious enhancement. When the incident wavelength is above 650 nm, P3HT becomes transparent and only Si absorbs incident light.

At this region, despite the size of photoactive Si NW is fixed, a certain amount of absorption enhancement can still be observed as the thickness of organic coating is increased. For example, at the wavelength of 700 nm, we note that the absorption at T = 80 nm has a factor of 1.81 higher than the case of the uncoated NWs. This can be understood Selleckchem Adriamycin by electrostatic approximation. The absorption in Si NW is proportional to the factor of |E core / E inc|2, where E core and E inc are the electric field intensity in the core and incident light of Si NW, respectively [17]. In the absence of the organic coating, |E core / E inc|2 = |2ϵ ext

/ (ϵ ext + ϵ core)|2 = 0.0169, where ϵ ext = 1 is the dielectric function of the vacuum exterior to selleck chemical the NW, and ϵ core ≈ 14.34 + 0.0985i is the dielectric function (for λ = 700 nm) of the Si NW. When an organic coating is added, |E core / E inc|2 = |2ϵ ext / (ϵ ext + ϵ coat)|2|2ϵ coat / (ϵ coat + ϵ core)|2 = 0.030, where ϵ coat = 3.75 is the dielectric function (for λ = 700 nm) of P3HT. About 1.78 times enhancement can be obtained at organic coating T = 80 nm than that of uncoated NWs, which is close to the absorptance enhancement at this wavelength Tolmetin (as shown in Figure 2c). Obviously, above the cutoff of P3HT, the organic coating can serve as a non-absorbing dielectric shell, which drastically increased the absorption in vertical semiconductor NWs. Moreover, at the wavelength larger than

650 nm, the extinction coefficient of silicon is small and interference effects exist, resulting in the oscillation of reflectance and transmittance [6]. Figure 2 Optical characteristics of the hybrid solar cells with various P3HT coating thicknesses. (a) Reflection. (b) Transmission. (c) Absorption. In order to understand the propagation of light in the hybrid solar cells, we simulated the electrical field intensity and calculated the optical generation rates within the arrays from where ϵ″ is the imaginary part of the complex permittivity and E is the electric field [18]. We give the optical generation rates for conformal coating hybrid structure with 80-nm P3HT at three typical wavelengths of 400, 600, and 700 nm. The optical generation rates of the uncoated Si NWs are used as comparison.

Several genes encoding proteases and protein modification enzymes

Several genes encoding proteases and protein modification enzymes such as ClpP1, ClpP2, ClpX, Lon, HslUV, HflCKX, FtsH, HtpX and Dcp also showed significantly increased expression in the tolC mutant. In addition to protecting proteins from destruction or degradation

of the denatured ones the rpoH regulon also protects other macromolecules CP673451 molecular weight like DNA and RNA [17]. In the tolC mutant we observed increased expression of the gene encoding Mfd which recruits the DNA repair machinery to lesions, as well as genes such as mutM, recJ, topA and xerD encoding products known to maintain genomic integrity [20]. Reinforcing the idea of the tolC mutant strain being under stress, the expression of many transcripts encoding enzymes involved in detoxification and protection against oxidative stress was increased. Examples include gst1, gst4, gst7 and gst11, all of which encode glutathione S-transferases. Glutathione transferase proteins catalyze nucleophilic attack by the tripeptide glutathione (GSH) on a wide range of hydrophobic toxic compounds. They are also capable of non-catalytically binding a large number of endogenous compounds, playing an AZD5582 purchase active role in protection against oxidative stress and detoxification of harmful xenobiotics [21]. Other genes with increased expression were

katA (3.7-fold) encoding a catalase, sodB (2.4-fold) encoding a superoxide dismutase, cpo (2.5-fold) encoding a chloride peroxidase, and gor (1.8-fold) encoding a glutathione reductase. Gene thtR showed the greatest expression in this functional class with a 29.3-fold increase (Table 1). thtR encodes a protein LY294002 homologous to tiosulphate sulfurtransferases of the Rhodanese family, which catalyze the transfer of the sulphate atom of thiosulphate to cyanide, to form sulphite and thyocianate. Several studies indicate that these proteins may function as antioxidants capable of scavenging oxidative species that would otherwise lead to inactivation of enzymes such as those containing Fe-S clusters [22]. To confirm microarray data and demonstrate that the tolC mutant is under oxidative stress, enzymatic activities

of catalase, superoxide dismutase and glutathione reductase were determined in cells grown in GMS medium for 20 hours (Fig. 4). Results showed that the specific activity of glutathione reductase in the total protein extract of the tolC mutant was twice that of the wild-type strain (Fig. 4a). In-gel activity staining was used to visualize catalase activity. Despite increased expression of the katA gene and decreased katB expression compared to the wild-type strain, increased catalase activity was detected in the tolC mutant (Fig. 4b). SOD activity was also higher in the tolC mutant (Fig. 4c). The active SodB protein is a dimer [23] and corresponds probably to the lower band, while the upper band must be a multimeric form.

Thus, E195 and E368 (marked

Thus, E195 and E368 (marked CX-6258 mouse with two boxes), which located in two conserved regions, were thought to be the active site residues of Gal308 based on amino acid sequence alignment and the determined structure of β-galactosidase from T. Thermophilus (Figure 1). Figure 1 Identification of the active site residues of Gal308 by alignment of the amino acid residues with other five homologous

β-galactosidases from GH family 42. The GenBank accession numbers are as follows: Geobacillus thermocatenulatus, AAW56416; Truepera radiovictrix DSM17093, ADI14846; Thermus thermophilus, ABI35985; Alicyclobacillus acidocaldarius, AAZ81841; Bacillus circulans, AAA22260; This study (Gal308), AFD21844. The alignment was carried out using the Clustal W method. The number flanking the sequences represents amino acid positions of each sequence. Asterisks mean identity. The two putative catalytic residues (E195 and E368) of Gal308 were shown in box. Heterologous expression and purification of recombinant Epigenetics inhibitor Gal308 To investigate the biochemical properties of Gal308, E. coli expression vector pET-32a(+) was used to express recombinant protein under the conditions described in materials and methods.

The cells were harvested and disrupted by sonication in ice-water bath. The cell lysate was found fully clear, and no inclusion bodies were formed, which suggested that the recombinant Gal308 was highly soluble. Then, the recombinant Lac308 with a six-histidine tag was purified by Ni-NTA chromatography, and the result showed that Ni-NTA chromatography of cell lysate led to 6.25-fold purification and 85% activity yield (Table 1). Furthermore, the purified

enzyme and the crude enzyme (supernatant from cell lysates) were applied to SDS-PAGE (Figure 2) together to determine the molecular mass and expression level of recombinant protein. The purified recombinant protein showed a single protein band of approximate 95 kDa, higher than its calculated molecular mass (76.77 kDa), which can be ascribed to its N-terminal fusion of 156 amino acids (about 18 kDa) corresponding to thioredoxin tag (Trx·Tag), polyhistidine tag (His·Tag), S·Tag epitope oxyclozanide (S·Tag), and a unique thrombin cleavage site (thrombin). In addition, the highest expression level of gal308 in E. coli was about 125 mg/L when the cell was induced at 30°C for 8 h. Next, the purified Gal308 was used to study its biochemical properties. Table 1 Purification of Gal308 Purification step Total protein (mg) Total activity (U) Specific activity (U/mg) Fold purification Activity yield (%) Cell lysate 37.94 1122.21 29.58 1.00 100.00% Ni-NTA chromatography 5.16 953.88 184.86 6.25 85.00% Figure 2 SDS-PAGE analysis of recombinant Gal308 from supernatant of E. coli BL21 (DE3) cell lysates and purified Gal308 by affinity chromatography. Lanes: M, standard protein molecular mass markers (sizes in kilodaltons are indicated on the left); 1, recombinant Gal308 from supernatant of E.

The wells in the second plate were carefully washed three times w

The wells in the second plate were carefully washed three times with PBS and then

used to determine the total number of adherent bacteria. All assays were performed in duplicate and repeated independently four times. Murine models of infection Six- to eight-week-old female CFW1 mice (Harlan) selleck chemicals were used for intestinal colonization experiments as described previously [64]. Briefly, mice were provided with drinking water containing 5 g/l streptomycin sulphate for 24 h and fed a 100 μl suspension containing ~109 CFU of each strain in 20% sucrose. On indicated days, faecal pellets were collected, weighed and homogenised in 0.9% NaCl and dilutions plated onto MacConkey agar supplemented Geneticin with appropriate antibiotics for faecal CFU counts.

A previously described intranasal infection model was used in a co-infection format [23]. Six- to eight-week-old female NMRi mice (Harlan) were anaesthetized and hooked on a string by their front teeth. 50 μl of bacterial suspension containing ~5 × 107 CFU of each strain was dropped onto the nares to allow for aspiration. Mice were left hooked on the string for 10 min before being returned to their cages. At sacrifice lungs, spleen and liver were collected in 0.9% NaCl and homogenised. Serial dilutions were plated on selective media for CFU counts. The ascending urinary tract infection model in which C3H mice (Harlan) were inoculated transurethrally

PDK4 with 50 μl of bacterial suspension containing ~5 × 108 CFU bacteria has been described in detail previously [22, 65]. All animal experiments were conducted under the auspices of the Animal Experiments Inspectorate, the Danish Ministry of Justice. Data analysis, statistics and nucleotide accession number Nucleotide sequences were annotated and analysed using the Integrative Services for Genomic Analysis software and manually curated [66]. The competitive index (CI) was calculated by dividing the ratio of fim2-positive to fim2-negative bacteria recovered from infected organs by the ratio of the corresponding bacteria in the initial inoculum. The non-parametric Mann–Whitney U test was used to analyse infection data. Biofilm and cell-adhesion data were analysed using the non-parametric Kruskal-Wallis test and Dunn’s posthoc analysis. The nucleotide sequence of KpGI-5 has been deposited online [GenBank: JN181158]. Acknowledgements We thank Jean-Marc Ghigo, Unité de Génétique des Biofilms, Institut Pasteur, France, for providing pKOBEG-Apra and Stefan Hyman, Centre for Core Biotechnology Services, University of Leicester, for electron microscopy analysis. This study was supported by a Medisearch research grant. JJvA was supported by a University of Leicester, 50th Anniversary PhD Scholarship. SGS was partially supported by the Danish Research Agency grant 2101-06-0009.

After a 6-week washout period where no training was performed, su

After a 6-week washout period where no training was performed, subjects were then randomly assigned to receive either

a protein supplement or a placebo immediately before and after resistance exercise. Training consisted of 6– 8 sets BV-6 in vivo of elbow flexion carried out 3 days a week for 12 weeks. No significant differences were found in muscle volume or anatomical cross-sectional area between groups. Discussion Despite claims that immediate post-exercise nutritional intake is essential to maximize hypertrophic gains, evidence-based support for such an “anabolic window of opportunity” is far from definitive. The hypothesis is based largely on the pre-supposition that training is carried out in a fasted state. During fasted exercise, a concomitant increase in muscle protein breakdown causes the pre-exercise net negative amino acid balance to persist in the post-exercise period despite training-induced increases in muscle protein selleck chemicals synthesis [36]. Thus, in the case of resistance training after an overnight fast, it would make sense to provide immediate nutritional intervention–ideally in the form of a combination of protein and carbohydrate–for the purposes of promoting muscle protein synthesis and reducing proteolysis, thereby switching a

net catabolic state into an anabolic one. Over a chronic period, this tactic could conceivably lead cumulatively to an increased rate of gains in muscle mass. This inevitably begs the question of how pre-exercise nutrition might influence the urgency or effectiveness of post-exercise nutrition, since not everyone engages in fasted training. In practice, it is common for those with the primary goal of increasing muscular size and/or

strength to make a concerted effort to consume a pre-exercise meal within 1-2 hours prior to the bout in attempt to maximize training performance. Depending on its size and composition, this meal can conceivably function as both a pre- and an immediate post-exercise Galactosylceramidase meal, since the time course of its digestion/absorption can persist well into the recovery period. Tipton et al. [63] observed that a relatively small dose of EAA (6 g) taken immediately pre-exercise was able to elevate blood and muscle amino acid levels by roughly 130%, and these levels remained elevated for 2 hours after the exercise bout. Although this finding was subsequently challenged by Fujita et al. [64], other research by Tipton et al. [65] showed that the ingestion of 20 g whey taken immediately pre-exercise elevated muscular uptake of amino acids to 4.4 times pre-exercise resting levels during exercise, and did not return to baseline levels until 3 hours post-exercise. These data indicate that even minimal-to-moderate pre-exercise EAA or high-quality protein taken immediately before resistance training is capable of sustaining amino acid delivery into the post-exercise period.

The production of these compounds is associated with hypo-osmotic

The production of these compounds is associated with hypo-osmotic stress tolerance in rhizobia [47]. The higher sensitivity of the rosR mutants to hypo-osmotic stress might be explained by increased check details permeability of their cell envelopes, which could allow excretion of greater amounts of neutral polysaccharides. Recently, several other osmotically unstable rhizobial mutants have been described, among them salt-sensitive mutants of S. meliloti, some of them significantly affected in competing against the wild type for nodule occupancy [48]. Mutation in S. meliloti regulatory gene nesR affected competition for nodulation, adaptation to high osmolarity, and nutrient

starvation [49]. Also, genes encoding trehalose biosynthesis pathways and potassium uptake systems were found to be important for S. meliloti growth in hyperosmotic medium [50, 51]. R. leguminosarum bv. trifolii rosR mutants deficient in EPS production grew considerably slower than the wild type on minimal medium. Using the Biolog system, we established that the rosR mutant revealed differences in utilization of carbon and nitrogen sources in relation to the wild

type. Similarly, phenotypic analysis of S. meliloti exoS and chvI null mutants demonstrated that ExoS/ChvI regulatory system not only controls succinoglycan (EPS I) and galactoglucan (EPS II) synthesis but is also required for growth on over 21 different carbon sources [52]. Molecular motor The chvI mutant exhibited Batimastat datasheet several pleiotropic effects: failed to grow on complex medium, had an altered LPS profile, exhibited lower tolerance to acidic conditions, was hypermotile, and synthesized significantly less poly-3-hydroxybutyrate than wild type, indicating that ChvI is engaged in regulatory networks involving the cell envelope and metabolism [53]. In several studies, a connection between the production of bacterial polysaccharides and motility has been established. Both R. leguminosarum bv. trifolii

rosR mutants and the pssA mutant deficient in EPS production exhibited a significant decrease in motility. S. meliloti MucR protein that simultaneously acts as a transcriptional repressor of galactoglucan synthesis and an activator of succinoglycan synthesis [25, 54] inhibits the expression of rem encoding an activator of the expression of such genes as flaF and flgG [55]. Other regulatory proteins, such as the ExpR/Sin quorum system, are additionally engaged in the regulation of S. meliloti motility [56, 57]. A non-motile phenotype has also been described for ndvA and ndvB mutants defective in the synthesis of β-(1,2)-glucans under hypo-osmotic conditions [58, 59]. Alterations in the LPS structure often cause motility-related defects [60, 61]. The R. leguminosarum bv. viciae 3841 LPS mutant mentioned earlier was impaired in motility and biofilm formation.

All of the following results for these adsorbates are obtained ba

The corresponding adsorption energy is determined to be -211 meV. The CO molecule somewhat

favors both H and B sites, giving an identical absorption energy of -128 meV (see Figure 1g). For simplicity, the configuration at the H site is chosen as the representative for CO. All of the following results for these adsorbates are obtained based on their most favorable configurations if not specified. Table 1 Results for gas molecules on monolayer MoS 2 calculated by LDA functional Gas H site TMsite TSsite B site h E a ΔQ h E a ΔQ h E Selleckchem MAPK inhibitor a ΔQ h E a ΔQ H2 2.62 -70 0.004 2.61 -82 0.004 3.02 -49 0.008       O2 2.79 -106 0.034 2.71 -116 0.041 3.19 -64 0.020       H2O 2.59 -234 0.012 2.67 -222 0.016 3.13 -110 0.009       NH3 2.46 -250 -0.069 2.61 -222 -0.051 3.21 -100 -0.024       NO 2.68 -195 0.011 2.90 -185 0.011 2.88 -152 0.039 2.83 -211 0.022 NO2 2.65 -276 0.100       2.71 -249 0.119 2.62 -249 0.114 CO 2.95 -128 0.020 3.22 -124 0.006 3.28 -86 0.016 3.15 -128 0.013 Equilibrium height between the center of mass of the molecule and the top S-layer of the MoS2 sheet (h, in Å), adsorption energy (E a , in meV), and charge transfer from MoS2 to the molecule (ΔQ, click here in e). Negative ΔQ means charge transfer from the molecule to

MoS2. Figure 1 Adsorption configurations. Top and side views of the most favorable configurations for (a) H2, (b) O2, (c) H2O, (d) NH3, (e) NO, (f) NO2, and (g) CO on monolayer MoS2. The blue and yellow balls represent Mo and S atoms, whereas the cyanine, red, gray, and black balls represent H, O, N, and C atoms, respectively. Additionally, calculations of the gas adsorption are also these performed using GGA functional. Different from LDA functional which overestimates the adsorption energy, GGA functional usually has a tendency to underestimate it. Upon the application of the two kinds of functionals, the upper and lower bounds for adsorption

energy and other structural properties can be obtained [8]. The calculated values of equilibrium height and adsorption energy for gas molecules on MoS2 are listed in Table 2. Herein, two GGA functionals, PW91 and PBE, are used for the purpose of comparison. Both PW91 and PBE give a smaller adsorption energy compared to the LDA, whereas they show the molecules binding at an equilibrium height larger than that for LDA. For most molecules (with the exception of NO), it seems that PW91 gives more stable results than PBE, with their adsorption energy difference approximately between -7 and -28 meV. Table 2 Results for gas molecules on monolayer MoS 2 calculated by PW91 and PBE functionals Gas Site LDA GGA-PW91 GGA-PBE h E a h E a h E a H2 TM 2.61 -82 3.21 -4 3.07 6 O2 TM 2.71 -116 3.32 -11 3.40 -4 H2O H 2.59 -234 3.17 -37 3.14 -21 NH3 H 2.46 -250 2.99 -44 2.91 -24 NO B 2.83 -211 3.47 -14 3.25 -33 NO2 H 2.65 -276 3.33 -43 3.30 -15 CO H 2.95 -128 3.61 -13 3.

Competition assays were performed with nuclear extracts from cell

Competition assays were performed with nuclear extracts from cells infected with Corby for 2 h. 100-fold excess amounts of competitor were added (lanes 3 to 5). A supershift assay in the same nuclear extracts also was performed. Antibodies (Ab) were added (lanes 6 to 10). Arrows indicate specific complexes, while arrowheads indicate the DNA binding complexes supershifted. (C) Flagellin-induced p65 translocation. Cells were infected with Corby or flaA mutant. Nuclear extracts were subjected to immunoblotting. (D) Flagellin activates buy GDC-0973 NF-κB through the classical and alternative pathways. Cells were infected with Corby or flaA mutant. Lysates were subjected

to immunoblotting. (E) Overexpression of dominant negative mutants inhibits L. pneumophila-induced activation of the IL-8 promoter. Cells were transfected with -133-luc and the mutant plasmids

and then infected with Corby for 6 h. The solid bar Idasanutlin in vitro indicates luciferase activity of -133-luc and empty vector without infection. Activity is expressed relative to that of cells transfected with -133-luc with further Corby infection, which was defined as 100. Data are means ± SD values of three experiments. dn, dominant negative. *, P < 0.05; **, P < 0.001 (by Student t test). As described above, the flaA mutant strain failed to induce mRNA expression and production of IL-8. Next, we determined whether the flaA mutant strain induces NF-κB DNA binding activity. As expected, NF-κB DNA binding activity was not induced by the isogenic flaA mutant, unlike the wild-type strain Corby (Fig.

6A). These results indicate that better activation Cell press of NF-κB binding by flaA-positive strain is the underlying mechanism of the observed activation of the IL-8 promoter by this bacterial strain. Considered together, these results indicate that L. pneumophila infection induces IL-8 gene expression at least in part through the induced binding of p50 and p65 NF-κB family members to the NF-κB element of the IL-8 promoter and that this effect is dependent on flagellin. Because nuclear translocation is a key step for transcriptional activity [9], we next examined whether L. pneumophila induces the nuclear translocation of NF-κB. As shown in Fig. 6C, the wild-type Corby, but not the flaA mutant, induced nuclear translocation of NF-κB. NF-κB is normally present in the cytoplasm in an inactive state and is bound to members of the IκB inhibitor protein family, chiefly IκBα. In this complex, IκBα blocks the nuclear localization signal, thus preventing nuclear translocation. Translocation of NF-κB into the nucleus requires disruption of the cytoplasmic NF-κB:IκBα complex [9]. To determine the role of IκBα phosphorylation and degradation in L. pneumophila-induced NF-κB translocation and activation, we investigated whether L. pneumophila induces phosphorylation and degradation of IκBα.

Astron Astrophys 378:597–607CrossRef Pino T et al (2008) The 6 2 

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composition of presolar grains from primitive meteorites. Ann Rev Earth Planet Sci 26:147–188CrossRef”
“This last issue of OLEB of 2011 contains a collection of papers from ORIGINS 2011. The conference, which was jointly organized by Bioastronomy (IAU Commission 51) and ISSOL, was held in Montpellier, France from 3 to 8 July, 2011. EVP4593 nmr The joint meeting was an experiment for both organizations and was universally considered to have been a great success. It has been decided to repeat the exercise and the next conference will be held in 2014 in Nara, Japan. OLEB congratulates the two societies and, particularly, the Local Organizing Committee of ORIGINS 2011, which was chaired by Muriel Gargaud and Robert Pascal. ORIGINS 2011 photo by Innovaxiom (Paris). Open Access This article is distributed under the

terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.”
“Introduction Lipmann (1965) assumed that, on the phosphate side, ‘the group potential might have originated with inorganic pyrophosphate (PPi) as the primitive group carrier’. The discovery that photosynthetic bacterial membrane-bound inorganic pyrophosphatase (PPase) catalyzed light-induced NADPH-cytochrome-c2 reductase phosphorylation of orthophosphate (Pi) to pyrophosphate (Baltscheffsky et al. 1966) and the capability of PPi to drive energy requiring dark reactions (Baltscheffsky

1967) supported pyrophosphate as a possible early alternative to adenosine triphosphate (ATP), the main chemical energy currency in living cells. Like the adenosine triphosphatase (ATPase), the corresponding membrane-bound PPase is also a H+-pump (Moyle et al. 1974), and can be a Na+-pump in both archaeal and bacterial membranes (Malinen et al. 2007). Support has been obtained for an earlier transport of Na+ than of H+ through biomembranes (Mulkidjanian et al. 2008a). The hyperthermophilic bacterium Thermotoga maritima, found in hydrothermal environments, as well as the mesophilic Methanosarcina mazei contain membrane-bound PPases (Tm-PPase and Mm-PPase, respectively) that are homologous to H+-PPases (Belogurov et al. 2005; Malinen et al. 2008). Both Tm-PPase and Mm-PPase have an absolute requirement for Na+, but display maximal activity in the presence of millimolar levels of K+.