The amino acid composition of proteins from anaero

Authors: Rahel Elevi Bardavid Aharon Oren

Publish Date: 2012/04/19

Volume: 16, Issue: 3, Pages: 567-572

PDF Link

Abstract

We performed a comparative analysis of the genome sequences of three anaerobic halophilic fermentative bacteria belonging to the order Halanaerobiales Halanaerobium praevalens the alkaliphilic “Halanaerobium hydrogeniformans” and the thermophilic Halothermothrix orenii to assess the amino acid composition of their proteins Members of the Halanaerobiales were earlier shown to accumulate KCl rather than organic compatible solutes for osmotic balance and therefore the presence of a dominantly acidic proteome was predicted Past reports indeed showed a large excess of acidic over basic amino acids in wholecell hydrolysates of selected members of the order However the genomic analysis did not show unusually high contents of acidic amino acids or low contents of basic amino acids The apparent excess of acidic amino acids in these anaerobic halophiles reported earlier is due to the high content in their proteins of glutamine and asparagine which yield glutamate and aspartate upon acid hydrolysis It is thus suggested that the proteins of the Halanaerobiales which are active in the presence of high intracellular KCl concentrations do not possess the typical acidic signature of the ‘halophilic’ proteins of the Archaea of the order Halobacteriales or of the extremely halophilic bacterium Salinibacter

Keywords: