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Publication Abstract from PubMed

The ubiquitous sulfur metabolite ergothioneine is biosynthesized by oxidative attachment of a sulfur atom to the imidazole ring of Nalpha-trimethylhistidine. Most actinobacteria, including Mycobacterium tuberculosis, use gamma-glutamyl cysteine as a sulfur donor. In subsequent steps the carbon scaffold of gamma-glutamyl cysteine is removed by the glutamine amidohydrolase EgtC and the beta-lyase EgtE. We determined the crystal structure of EgtC from Mycobacterium smegmatis in complex with its physiological substrate. The set of active site residues that define substrate specificity in EgtC are highly conserved, even in homologues that are not involved in ergothioneine production. This conservation is compounded by the phylogenetic distribution of EgtC-like enzymes indicates that their last common ancestor might have emerged for a purpose other than ergothioneine production.

Structure of the Ergothioneine-Biosynthesis Amidohydrolase EgtC.,Vit A, Mashabela GT, Blankenfeldt W, Seebeck FP Chembiochem. 2015 Jun 16. doi: 10.1002/cbic.201500168. PMID:26079795^[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.