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O-ACETYLSERINE SULFHYDRYLASE FROM SALMONELLA TYPHIMURIUMO-ACETYLSERINE SULFHYDRYLASE FROM SALMONELLA TYPHIMURIUM
Structural highlights
FunctionCYSK_SALTY Two cysteine synthase enzymes are found. Both catalyze the same reaction. Cysteine synthase B can also use thiosulfate in place of sulfide to give cysteine thiosulfonate as a product. 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 last step in cysteine biosynthesis in enteric bacteria is catalyzed by the pyridoxal 5'-phosphate-dependent enzyme O-acetylserine sulfhydrylase. Here we report the crystal structure at 2.2 A resolution of the A-isozyme of O-acetylserine sulfhydrylase isolated from Salmonella typhimurium. O-acetylserine sulfhydrylase shares the same fold with tryptophan synthase-beta from Salmonella typhimurium but the sequence identity level is below 20%. There are some major structural differences: the loops providing the interface to the alpha-subunit in tryptophan synthase-beta and two surface helices of tryptophan synthase-beta are missing in O-acetylserine sulfhydrylase. The hydrophobic channel for indole transport from the alpha to the beta active site of tryptophan synthase-beta is, not unexpectedly, also absent in O-acetylserine sulfhydrylase. The dimer interface, on the other hand, is more or less conserved in the two enzymes. The active site cleft of O-acetylserine sulfhydrylase is wider and therefore more exposed to the solvent. A possible binding site for the substrate O-acetylserine is discussed. Three-dimensional structure of O-acetylserine sulfhydrylase from Salmonella typhimurium.,Burkhard P, Rao GS, Hohenester E, Schnackerz KD, Cook PF, Jansonius JN J Mol Biol. 1998;283(1):121-33. PMID:9761678[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References |
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