PH‐Dependent hydrolase, glutaminase, transpeptidase and autotranspeptidase activities of Bacillus subtilis γ‐glutamyltransferase. (26th November 2013)

• Record Type: Journal Article
• Authors: Morelli, Carlo F.; Calvio, Cinzia; Biagiotti, Marco; Speranza, Giovanna
• Is Part Of: FEBS journal. Volume 281:Number 1(2014)
• Page Start: 232
• Page End: 245
• Publication Date: 2013-11-26
• Subjects: Biochemistry -- Periodicals; Molecular biology -- Periodicals; Pathology, Molecular -- Periodicals; 572
• DOI: 10.1111/febs.12591
• Languages: English
• ISSNs: 1742-464X

Abstract

<abstract abstract-type="main" id="febs12591-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <p>γ‐Glutamyltransferases (γ‐GTs) are heterodimeric enzymes that catalyze the transfer of a γ‐glutamyl group from a donor species to an acceptor molecule in a transpeptidation reaction through the formation of an intermediate γ‐glutamyl enzyme. In our search for a γ‐GT from a generally recognized as safe microorganism suitable for the production of γ‐glutamyl derivatives with flavor‐enhancing properties intended for human use, we cloned and overexpressed the γ‐GT from <italic>Bacillus subtilis</italic>. In this study, we report the behavior of <italic>B. subtilis</italic> γ‐GT in reactions involving glutamine as the donor compound and various acceptor amino acids. The common thread emerging from our results is a strong dependence of the hydrolase, transpeptidase and autotranspeptidase activities of <italic>B. subtilis</italic> γ‐GT on pH, also in relation to the p<italic>K</italic><sub>a</sub> of the acceptor amino acids. Glutamine, commonly referred to as a poor acceptor molecule, undergoes rapid autotranspeptidation at elevated pH, affording oligomeric species, in which up to four γ‐glutamyl moieties are linked to a single glutamine. Moreover, we found that <sc>d</sc>‐glutamine is also recognized both as a donor and as an acceptor substrate. Our results prove that the <italic>B. subtilis</italic> γ‐GT‐catalyzed transpeptidation reaction is feasible, and the observed activities of γ‐GT from <italic>B. subtilis</italic> could be interpreted in relation to the known ability of the enzyme to process the polymeric material γ‐polyglutamic acid.</p> </abstract>