β-Glutamate as a Substrate for Glutamine Synthetase
Links to Fileshttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC93190/
MetadataShow full item record
Type of Work6 pages
Citation of Original PublicationPatrice Robinson, Kelly Neelon, Harold J. Schreier, and Mary F. Roberts, β-Glutamate as a Substrate for Glutamine Synthetase, Appl Environ Microbiol. 2001 Oct; 67(10): 4458–4463. doi: 10.1128/AEM.67.10.4458-4463.2001
RightsThis item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.
The conversion of β-glutamate to β-glutamine by archaeal and bacterial glutamine synthetase (GS) enzymes has been examined. The GS from Methanohalophilus portucalensis (which was partially purified) is capable of catalyzing the amidation of this substrate with a rate sevenfold less than the rate obtained with α-glutamate. Recombinant GS from the archaea Methanococcus jannaschii and Archaeoglobus fulgidus were considerably more selective for α-glutamate than β-glutamate as a substrate. All the archaeal enzymes were much less selective than the two bacterial GS (from Escherichia coli and Bacillus subtilis), whose specific activities towards β-glutamate were much smaller than rates with the α-isomer. These results are discussed in light of the observation that β-glutamate is accumulated as an osmolyte in many archaea while β-glutamine (produced by glutamine synthetase) is used as an osmolyte only in M. portucalensis.