The amino acid composition of proteins from anaerobic halophilic bacteria of the order Halanaerobiales

Rahel Elevi Bardavid, Aharon Oren*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

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 whole-cell 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.

Original languageAmerican English
Pages (from-to)567-572
Number of pages6
JournalExtremophiles
Volume16
Issue number3
DOIs
StatePublished - May 2012

Bibliographical note

Funding Information:
Acknowledgments We thank Omri Finkel for assistance with the data processing. This study was supported by grant no. 1103/10 from the Israel Science Foundation.

Keywords

  • Acidic proteins
  • Anaerobic
  • Halanaerobiaceae
  • Halophilic
  • Osmotic adaptation

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