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Does anyone know of any papers showing how Gram positive Fermiculates or Actinobacteria use a H+ gradient for an F-type ATPase, It seems impossible since there is no outer LPS membrane to maintain the protons in a periplasmic space. Is the use of ATPase for production of ATP exclusively a Gram negative thing?

I found this question "Production of ATP in Lactobacilli" but no answers: Production of ATP in Lactobacilli

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Don't have an answer, but it seems to me that given that the Gram negative outer membrane is stuffed full of porins, there is no barrier to proton loss in this case either. –  Alan Boyd Mar 31 at 14:35
    
@AlanBoyd Are porins permeable to hydronium ions as well as water? –  Superbest Apr 1 at 23:25
    
found this on wiki: This cation is often used to represent the nature of the proton in aqueous solution, where the proton is highly solvated (bound to a solvent). The reality is far more complicated, as a proton is bound to several molecules of water, such that other descriptions such as H5O2+, H7O3+ and H9O4+ are increasingly accurate descriptions of the environment of a proton in water –  Jasand Pruski Apr 2 at 18:02
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1 Answer 1

Protons are pumped out of the bacterial cell by the electron tansport chain. This creates a protonmotive force with two components, one due to the difference in proton concentration, the other due to the membrane potential that is created. In bacteria and mitochondria it is the membrane potential component that provides most of the driving force to pull protons back in through the ATP synthase. Thus the fate of the protons outside the cell doesn't matter too much. Even if you were to buffer the exterior absolutely, the fact that charge had moved out would drive ATP synthesis.

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"the fact that charge had moved out would drive ATP synthesis." this is only true if the protons are going down a concentration gradient, if they work against the gradient ATP is being used not synthesized... –  Jasand Pruski Apr 1 at 15:14
    
unless there is chlorophyl involved (ex. chlorophyl G in Heliobacteria) and then there's some oxidoredux work dunno by which electron carrier... –  Jasand Pruski Apr 1 at 15:24
    
but what if a bunch of fermiculates are in a small space and the fluid isn't buffered, it could work as a community... –  Jasand Pruski Apr 1 at 15:40
    
In response to your first comment, protons would move up a proton concentration gradient if the membrane potential was favourable, until the chemical and electrical potentials were balanced. –  Alan Boyd Apr 1 at 17:13
    
do you know of a good review article on electric gradients causing a substance to move against a chemical gradient in a biological context? –  Jasand Pruski Apr 2 at 18:08
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