pH optimum

Edge evidence

• external pH imposes gradient of proton METPO:2007601

  External pH imposes a transmembrane H+ gradient on the cell.

  • DOI:10.1016/j.tim.2007.02.005 major contributor to the proton motive force Supports the transmembrane H+ gradient as the determinant of the proton motive force.
• cytoplasmic pH homeostasis regulates proton motive force RO:0002211

  Cytoplasmic pH homeostasis maintains a balanced proton motive force at the optimal external pH.

  • DOI:10.1038/nrmicro2549 pH homeostasis Supports pH homeostasis as the mechanism balancing the proton motive force.
• proton motive force enables maximal growth rate RO:0002327

  A balanced proton motive force enables peak growth.

  • DOI:10.1016/j.tim.2007.02.005 proton motive force Supports the proton motive force as the energetic basis of growth at the optimal external pH.
• maximal growth rate manifests as pH optimum METPO:2007400

  The external pH supporting peak growth manifests the pH-optimum phenotype.

  • DOI:10.1038/nrmicro2549 cytoplasmic pH Supports the trait endpoint.
• external pH contributes to proton motive force RO:0002326

  The external pH largely determines the magnitude of the pH gradient (ΔpH) component of the proton motive force.

  • DOI:10.1093/femsre/fuad033 Cells maintain cytoplasmic pH near neutral, so the magnitude of the pH gradient is largely determined by the external pH.
• proton motive force drives ATP synthesis by F0F1-ATP synthase

  The proton motive force drives ATP synthesis via the F0F1-ATP synthase.

  • DOI:10.1093/femsre/fuad033 PMF drives the synthesis of ATP; the F0F1-ATP synthase uses three to five protons to synthesize one ATP.
• Na+/H+ antiporter activity enables cytoplasm acidification RO:0002327

  Proton-sensing Na+/H+ (and K+/H+) antiporters acidify the cytoplasm when internal pH gets too high.

  • DOI:10.1093/femsre/fuad033 Proton-sensing ion/H+ antiporters acidify the cytoplasm by exporting K+ or Na+ in exchange for protons when the internal pH gets too high.
• cytoplasm acidification regulates cytoplasmic pH homeostasis RO:0002211

  Antiporter-driven cytoplasm acidification contributes to cytoplasmic pH homeostasis.

  • DOI:10.1093/femsre/fuad033 Acidifying the cytoplasm when internal pH gets too high is a homeostatic mechanism maintaining near-neutral cytoplasmic pH.
• metabolite decarboxylation pathways contributes to cytoplasmic pH homeostasis RO:0002326

  Proton-consuming decarboxylation reactions raise the internal pH and contribute to pH homeostasis.

  • DOI:10.1093/femsre/fuad033 The chemistry of the decarboxylation reaction requires a proton, raising internal pH, and the enzymes have a built-in self-regulatory mechanism contributing to pH homeostasis.
• metabolite decarboxylation pathways generates proton motive force biolink:produces

  Free energy from decarboxylation reactions can be stored as a proton motive force.

  • DOI:10.1093/femsre/fuad033 The free energy change from decarboxylation reactions can be stored in the form of a proton motive force.
• cytoplasmic buffering capacity regulates internal pH RO:0002211

  Cytoplasmic buffering capacity stabilizes the internal pH by absorbing pH fluctuations.

  • DOI:10.1093/femsre/fuad033 The buffering capacity of the cytoplasm is important in absorbing pH fluctuations (e.g. inorganic and organic phosphates).