6tcc
Crystal structure of Salmo salar RidA-1
Structural highlights
FunctionA0A1S3KNQ3_SALSA Catalyzes the hydrolytic deamination of enamine/imine intermediates that form during the course of normal metabolism. May facilitate the release of ammonia from these potentially toxic reactive metabolites, reducing their impact on cellular components. It may act on enamine/imine intermediates formed by several types of pyridoxal-5'-phosphate-dependent dehydratases including L-threonine dehydratase.[ARBA:ARBA00002596] Publication Abstract from PubMedReactive Intermediate Deaminase (Rid) protein superfamily includes eight families among which the RidA is conserved in all domains of life. RidA proteins accelerate the deamination of the reactive 2-aminoacrylate (2AA), an enamine produced by some pyridoxal phosphate (PLP)-dependent enzymes. 2AA accumulation inhibits target enzymes with a detrimental impact on fitness. As a consequence of whole genome duplication, teleost fish have two ridA paralogs, while other extant vertebrates contain a single-copy gene. We investigated the biochemical properties of the products of two paralogs, identified in Salmo salar. SsRidA-1 and SsRidA-2 complemented the growth defect of a Salmonella enterica ridA mutant, an in vivo model of 2AA stress. In vitro, both proteins hydrolyzed 2-imino acids (IA) to keto-acids and ammonia. SsRidA-1 was active on IA derived from nonpolar amino acids and poorly active or inactive on IA derived from other amino acids tested. In contrast, SsRidA-2 had a generally low catalytic efficiency, but showed a relatively higher activity with IA derived from L-Glu and aromatic amino acids. The crystal structures of SsRidA-1 and SsRidA-2 provided hints of the remarkably different conformational stability and substrate specificity. Overall, SsRidA-1 is similar to the mammalian orthologs whereas SsRidA-2 displays unique properties likely generated by functional specialization of a duplicated ancestral gene. Two novel fish paralogs provide insights into the Rid family of imine deaminases active in pre-empting enamine/imine metabolic damage.,Digiovanni S, Visentin C, Degani G, Barbiroli A, Chiara M, Regazzoni L, Di Pisa F, Borchert AJ, Downs DM, Ricagno S, Vanoni MA, Popolo L Sci Rep. 2020 Jun 23;10(1):10135. doi: 10.1038/s41598-020-66663-w. PMID:32576850[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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