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Structure of P. aeruginosa acetyltransferase PA4866 solved in complex with L-Methionine sulfoximine
Structural highlights
FunctionMDDA_PSEAE Plays a role in the resistance against the toxic effects of L-methionine sulfoximine (MSX), a rare amino acid, which inhibits glutamine synthetase (GlnA). Catalyzes the acetylation of L-methionine sulfoximine (MSX).[UniProtKB:A6VCX3] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe gene PA4866 from Pseudomonas aeruginosa is documented in the Pseudomonas genome database as encoding a 172 amino acid hypothetical acetyltransferase. We and others have described the 3D structure of this protein (termed pita) [Davies et al. (2005) Proteins: Struct., Funct., Bioinf. 61, 677-679; Nocek et al., unpublished results], and structures have also been reported for homologues from Agrobacterium tumefaciens (Rajashankar et al., unpublished results) and Bacillus subtilis [Badger et al. (2005) Proteins: Struct., Funct., Bioinf. 60, 787-796]. Pita homologues are found in a large number of bacterial genomes, and while the majority of these have been assigned putative phosphinothricin acetyltransferase activity, their true function is unknown. In this paper we report that pita has no activity toward phosphinothricin. Instead, we demonstrate that pita acts as an acetyltransferase using the glutamate analogues l-methionine sulfoximine and l-methionine sulfone as substrates, with Km(app) values of 1.3 +/- 0.21 and 1.3 +/- 0.13 mM and kcat(app) values of 505 +/- 43 and 610 +/- 23 s-1 for l-methionine sulfoximine and l-methionine sulfone, respectively. A high-resolution (1.55 A) crystal structure of pita in complex with one of these substrates (l-methionine sulfoximine) has been solved, revealing the mode of its interaction with the enzyme. Comparison with the apoenzyme structure has also revealed how certain active site residues undergo a conformational change upon substrate binding. To investigate the role of pita in P. aeruginosa, a mutant strain, Depp4, in which pita was inactivated through an in-frame deletion, was constructed by allelic exchange. Growth of strain Depp4 in the absence of glutamine was inhibited by l-methionine sulfoximine, suggesting a role for pita in protecting glutamine synthetase from inhibition. l-Methionine sulfoximine, but not phosphinothricin, is a substrate for an acetyltransferase (gene PA4866) from Pseudomonas aeruginosa: structural and functional studies.,Davies AM, Tata R, Beavil RL, Sutton BJ, Brown PR Biochemistry. 2007 Feb 20;46(7):1829-39. Epub 2007 Jan 25. PMID:17253769[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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