The archaeal-bacterial lipid divide, could a distinct lateral proton route hold the answer?

Mario Mencía

doi:10.1186/s13062-020-00262-7

Abstract

The archaea-bacteria lipid divide is one of the big evolutionary enigmas concerning these two domains of life. In short, bacterial membranes are made of fatty-acid esters whereas archaeal ones contain isoprenoid ethers, though at present we do not have a good understanding on why they evolved differently. The lateral proton transfer mode of energy transduction in membranes posits that protons utilize the solvation layer of the membrane interface as the main route between proton pumps and ATPases, avoiding dissipation of energy to the bulk phase. In this article I present the hypothesis on a proton-transport route through the ester groups of bacterial phospholipids as an explanation for the evolutionary divergence seen between bacteria and archaea.ReviewersThis article was reviewed by Uri Gophna (Editorial Board member) and Víctor Sojo.

Highlights

Bacteria have adapted to live in all environments found in the biosphere, and their diversity and biomass in mesophilic environments are unmatched by other organisms
Acknowledging that other scenarios are in discussion, the context for this hypothesis places the origin of bacteria branching out from an ancient, non-extant lineage sharing a common ancestor with archaea, dating back to the beginning of the population of mesophilic environments on Earth
Practical advantage of ester lipids Regardless of whether the ester membranes were acquired by bacteria from the beginning or subsequently derived from archaeal-like membranes, do the ester phospholipids membranes represent any advantage for bacteria, especially in mesophilic environments? Biological membranes, both archaeal and bacterial, obviously function under all conditions where we can find these organisms [9], so from an ecological perspective, there would be little grounds to prefer ester lipids to ether ones

Summary

Introduction

Bacteria have adapted to live in all environments found in the biosphere, and their diversity and biomass in mesophilic environments are unmatched by other organisms. Since archaeal ether membranes lack the carbonyl groups of the bacterial ester lipids, the hypothesis is that iLPT would be more efficient in bacteria than in archaea, in proportion to the actual contribution of the carbonyl groups to that transport.

Results

Conclusion