Be argued. The first one is that the F1Fo-ATPase extrudes

Be argued. The first one is that the F1Fo-ATPase extrudes protons to regulate pHi instead of the ATP synthesis at acidic pH. Such a function of the F1Fo-ATPase was first demonstrated in E. hirae (formerly S. faecalis) [13], and was also argued for in E. coli [1], although there has been no Title Loaded From File direct evidence to suggest it in E. coli. The second one is that E. coli has an unidentified system for pHi regulation whose operation is driven by ATP. The activity of this putative system is diminished by a decrease in the ATP level. The pHi was still regulated at a higher level in the medium even though no ATP was detected in the hemA mutant after the acidic challenge for 1 h (Table 2, and Fig. 3). This supports that ATP-independent systems such as amino acid decarboxylation operate to regulate pHi. The addition of glutamate and arginine could increase the viability of the F1Fo-ATPase mutants, but the survival was still lower than that of the wild type (Fig. 2), indicating that the amino acid systems alone are not sufficient for AR.pHo strains 5.5 2.5 15 min W3110 DK8 SE020 (atpD) SE023 (atpE) 7.1660.09 6.9860.20** 7.0460.14* 7.1360.15* 4.0860.03 3.6960.04** 3.6160.04** 3.5660.21** 3.7960.03** 30 min 3.9460.04 3.5460.07** 3.5760.13** 3.5860.18** 3.7160.07** 60 min 3.8260.04 3.5060.10** 3.5460.12** 3.5460.20** 3.6460.02*ConclusionsIntracellular pH affects the enzyme activity, protein stability, structure of nucleic acids, and functions of many other biological molecules. We found in the present study that respiration and the F1Fo-ATPase participate in pHi regulation and maintenance of the ATP content at a high level to enhance the AR of E. coli. Since pHi regulation is important for survival at acidic pH, E. coli is likely to have multiple systems for pHi regulation. In any case, it was strongly suggested that the 18325633 ATP-dependent metabolic processes enhance the survival at acidic pH even if growth stops and that pHi regulation is indispensable to keep such metabolic processes active.SE022 (hemA) 7.1560.pHi was measured as described in Materials and Methods. pHo is the pH values of the medium. The p-values compared with the wild type were calculated. * p,0.05 (n = 6); ** p,0.005 (n = 6). doi:10.1371/journal.pone.0052577.tRespiration and F1Fo-ATPase Enhance AR in E. coliAcknowledgmentsWe would like to express our thanks to T. Horie and M. Futai for use of the luminometer and supply of anitserum against the F1 part of the F1FoATPase, respectively.Author ContributionsConceived and designed the experiments: YS TF HS HK. Performed the experiments: YS. Analyzed the data: YS TF HS HK. Contributed reagents/materials/Title Loaded From File analysis tools: YS TF HS HK. Wrote the paper: YS TF HS HK.
The induction of adaptive cellular immunity is a function of professional antigen presenting cells (APCs) such as dendritic 1527786 cells, which provide signal 1 (peptide-major histocompatibility complex (MHC)), signal 2 (co-stimulatory molecules), and signal 3 (instructive cytokines) to naive T lymphocytes upon antigen encounter [1]. Endothelial cells (EC) form the inner lining of blood vessels and are positioned between circulating lymphocytes and peripheral tissues. As such, EC are the first cells with which T cells come into direct contact in the circulation. The hypothesis that EC may be able to act as APC is based upon the intimate interactions between EC in microvessels and T cells during transendothelial migration to lymph nodes or peripheral tissues. That is, EC may acquire antigenic protei.Be argued. The first one is that the F1Fo-ATPase extrudes protons to regulate pHi instead of the ATP synthesis at acidic pH. Such a function of the F1Fo-ATPase was first demonstrated in E. hirae (formerly S. faecalis) [13], and was also argued for in E. coli [1], although there has been no direct evidence to suggest it in E. coli. The second one is that E. coli has an unidentified system for pHi regulation whose operation is driven by ATP. The activity of this putative system is diminished by a decrease in the ATP level. The pHi was still regulated at a higher level in the medium even though no ATP was detected in the hemA mutant after the acidic challenge for 1 h (Table 2, and Fig. 3). This supports that ATP-independent systems such as amino acid decarboxylation operate to regulate pHi. The addition of glutamate and arginine could increase the viability of the F1Fo-ATPase mutants, but the survival was still lower than that of the wild type (Fig. 2), indicating that the amino acid systems alone are not sufficient for AR.pHo strains 5.5 2.5 15 min W3110 DK8 SE020 (atpD) SE023 (atpE) 7.1660.09 6.9860.20** 7.0460.14* 7.1360.15* 4.0860.03 3.6960.04** 3.6160.04** 3.5660.21** 3.7960.03** 30 min 3.9460.04 3.5460.07** 3.5760.13** 3.5860.18** 3.7160.07** 60 min 3.8260.04 3.5060.10** 3.5460.12** 3.5460.20** 3.6460.02*ConclusionsIntracellular pH affects the enzyme activity, protein stability, structure of nucleic acids, and functions of many other biological molecules. We found in the present study that respiration and the F1Fo-ATPase participate in pHi regulation and maintenance of the ATP content at a high level to enhance the AR of E. coli. Since pHi regulation is important for survival at acidic pH, E. coli is likely to have multiple systems for pHi regulation. In any case, it was strongly suggested that the 18325633 ATP-dependent metabolic processes enhance the survival at acidic pH even if growth stops and that pHi regulation is indispensable to keep such metabolic processes active.SE022 (hemA) 7.1560.pHi was measured as described in Materials and Methods. pHo is the pH values of the medium. The p-values compared with the wild type were calculated. * p,0.05 (n = 6); ** p,0.005 (n = 6). doi:10.1371/journal.pone.0052577.tRespiration and F1Fo-ATPase Enhance AR in E. coliAcknowledgmentsWe would like to express our thanks to T. Horie and M. Futai for use of the luminometer and supply of anitserum against the F1 part of the F1FoATPase, respectively.Author ContributionsConceived and designed the experiments: YS TF HS HK. Performed the experiments: YS. Analyzed the data: YS TF HS HK. Contributed reagents/materials/analysis tools: YS TF HS HK. Wrote the paper: YS TF HS HK.
The induction of adaptive cellular immunity is a function of professional antigen presenting cells (APCs) such as dendritic 1527786 cells, which provide signal 1 (peptide-major histocompatibility complex (MHC)), signal 2 (co-stimulatory molecules), and signal 3 (instructive cytokines) to naive T lymphocytes upon antigen encounter [1]. Endothelial cells (EC) form the inner lining of blood vessels and are positioned between circulating lymphocytes and peripheral tissues. As such, EC are the first cells with which T cells come into direct contact in the circulation. The hypothesis that EC may be able to act as APC is based upon the intimate interactions between EC in microvessels and T cells during transendothelial migration to lymph nodes or peripheral tissues. That is, EC may acquire antigenic protei.