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A novel limb in the osmoregulatory network of Methanosarcina mazei Gö1: N ε ‐acetyl‐β‐lysine can be substituted by glutamate and alanine
Author(s) -
Saum Regina,
Mingote Ana,
Santos Helena,
Müller Volker
Publication year - 2009
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/j.1462-2920.2008.01826.x
Subject(s) - lysine , alanine , biology , biochemistry , betaine , glycine , mutant , amino acid , gene
Summary N ε ‐acetyl‐β‐lysine is a unique compatible solute found in methanogenic archaea grown at high salinities. Deletion of the genes that encode the lysine‐2,3‐aminomutase ( ablA ) and the β‐lysine acetyltransferase ( ablB ) abolished the production of N ε ‐acetyl‐β‐lysine in Methanosarcina mazei Gö1. The mutant grew well at low and intermediate salinities. Interestingly, growth at high salt (800 mM NaCl) was only slowed down but not impaired demonstrating that in M. mazei Gö1 N ε ‐acetyl‐β‐lysine is not essential for growth at high salinities. Nuclear magnetic resonance (NMR) analysis revealed an increased glutamate pool in the mutant. In addition to α‐glutamate, a novel solute, alanine, was produced. The intracellular alanine concentration was as high as 0.36 ± 0.05 μmol (mg protein) −1 representing up to 18% of the total solute pool at 800 mM NaCl. The cellular alanine concentration increased with the salinity of the medium and decreased in the presence of glycine betaine in the medium, indicating that alanine is used as compatible solute by M. mazei Gö1.