title: Crystal structure of EstSRT1, a family VIII carboxylesterase displaying hydrolytic activity toward oxyimino cephalosporins.
abstract: EstSRT1 is a family VIII carboxylesterase that hydrolyzes oxyimino third- and fourth-generation cephalosporins, first-generation cephalosporins and ester substrates. According to the crystal structure of EstSRT1 (2.0-Å resolution), this protein contains a large α/β domain and a small α-helical domain and harbors three catalytic residues (Ser71, Lys74, and Tyr160) in the cavity at the domain interface, similarly to other family VIII carboxylesterases. Comparison of the structures of EstSRT1 and EstU1, a family VIII carboxylesterase with no hydrolytic activity toward bulky oxyimino cephalosporins, revealed that EstSRT1 has a smaller active site, despite its extended substrate range. The B-factors of the active site segments that could potentially contact with the oxyimino groups and the R2 side chains of oxyimino cephalosporins are higher in EstSRT1 than in EstU1, thus suggesting the role of the active site's structural flexibility in the extension of EstSRT1's substrate spectrum.
authors: Department of Chemistry & Nano Science, Ewha Womans University, Seoul, 03760, Republic of Korea. Electronic address: chajung@ewha.ac.kr.
authors: Sun-Shin
authors: SS
authors: Cha
authors: Marine Biotechnology Research Center, Korea Institute of Ocean Science and Technology, Ansan 426-744, Republic of Korea.
authors: Young Jun
authors: YJ
authors: An
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002265:Carboxylic Ester Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D020134:Catalytic Domain; D000077723:Cefepime; D002439:Cefotaxime / Q000737:chemistry* / Q000378:metabolism; D002511:Cephalosporins / Q000737:chemistry* / Q000378:metabolism; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D006868:Hydrolysis; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D054730:Protein Interaction Domains and Motifs; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D040681:Structural Homology, Protein
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002511:Cephalosporins; D007527:Isoenzymes; D011994:Recombinant Proteins; D000077723:Cefepime; D002265:Carboxylic Ester Hydrolases; D002439:Cefotaxime
keywords: Crystal structure; EstSRT1; Extended hydrolytic activity toward oxyimino cephalosporins; Family VIII carboxylesterases; Flexibility of the active site