pH range low

Edge evidence

• acidophile pH homeostasis enables pH range low RO:0002327

  Acidophile pH-homeostasis enables growth across pH 4–6.

  • DOI:10.1038/nrmicro2549 cytoplasmic pH Supports acidophile cytoplasmic pH homeostasis as the moderately-acidic growth-range mechanism.
• pH range low is a pH range rdfs:subClassOf

  pH range low is a quantitative bin of the pH-range phenotype.

  • DOI:10.1016/j.tim.2007.02.005 proton motive force Supports the pH 4–6 range as a value within the pH-range distribution.
• proton motive force drives ATP synthase-mediated ATP formation

  The proton motive force drives ATP synthase phosphorylation of ADP to ATP.

  • DOI:10.1111/1758-2229.70019 "That proton potential then drives the phosphorylation of ADP and the formation of ATP by the ATP synthase"; general bioenergetic edge relevant to low-pH growth.
• cyclopropane fatty acids decreases membrane proton permeability RO:0002212

  Cyclopropane fatty acid membrane modification decreases proton permeability.

  • DOI:10.4014/jmb.2303.03009 "decreasing membrane proton permeability prevents the accumulation of intracellular protons" after conversion to cyclopropane fatty acids; generalizable membrane adaptation.
• undissociated weak organic acids undergoes weak organic acid influx into cell

  At low external pH weak organic acids are undissociated and diffuse into the cell.

  • DOI:10.1111/1758-2229.70019 "organic acids... occur in their undissociated form and can diffuse into the cell"; boundary condition distinguishing low-pH growth from weak-acid inhibition.
• intracellular dissociation of weak organic acids lowers internal (cytoplasmic) pH

  Intracellular dissociation of weak organic acids releases protons and lowers cytoplasmic pH.

  • DOI:10.1111/1758-2229.70019 "the higher pH of the cytoplasm will lead to dissociation of the acid, thus releasing protons and lowering the internal pH"; strong causal edge.
• H+-ATPase proton efflux pump exports cytoplasmic protons METPO:2000209

  H+-ATPases actively export protons from the cytoplasm using ATP.

  • DOI:10.3389/fmicb.2023.1149903 Acidophile genomes encode "a P-type ATPase proton efflux pump"; active ATP-driven proton export underlies cytoplasmic pH homeostasis.
• H+-ATPase proton efflux pump contributes to acidophile pH homeostasis RO:0002326

  ATP-driven proton export by H+-ATPases contributes to acidophile pH homeostasis.

  • DOI:10.3390/microorganisms12030625 "acid stress tolerance... facilitated by an active export of protons via the expenditure of ATP... carried out by H+-ATPases"; broad principle of homeostasis.