title: Characterization of a new rhamnogalacturonan acetyl esterase from Bacillus halodurans C-125 with a new putative carbohydrate binding domain.
abstract: BH1115 is a gene from Bacillus halodurans strain C-125 that hypothetically encodes a rhamnogalacturonan acetyl esterase (RGAE) of the CE-12 family. As confirmation, this gene was cloned, and the product was expressed in Escherichia coli strain Rosetta (DE3) cells and purified. The enzyme obtained was monomeric, with a molecular mass of 45 kDa, and exhibited alkaliphilic properties. A study of the inhibition of the activity by some modulators confirmed that the catalytic triad for the esterase activity was Ser-His-Asp. This enzyme also presents broad substrate specificity and is active toward 7-aminocephalosporanic acid, cephalosporin C, p-nitrophenyl acetate, beta-naphthyl acetate, glucose pentaacetate, and acetylated xylan. Moreover, RGAE from B. halodurans achieves a synergistic effect with xylanase A toward acetylated xylan. As a member of the SGNH family, it does not adopt the common alpha/beta hydrolase fold. The homology between the folds of RGAE from Aspergillus aculeatus and the hypothetical YxiM precursor from Bacillus subtilis, which both belong to the SGNH family, illustrates the divergence of such proteins from a common ancestor. Furthermore, the enzyme possesses a putative substrate binding region at the N terminus of the protein which has never been described to date for any RGAE.
authors: Department of Biochemistry and Molecular Biology-A, Faculty of Biology, University of Murcia, Campus Espinardo, E-30071 Murcia, Spain.
authors: José
authors: J
authors: Navarro-Fernández
authors: Irene
authors: I
authors: Martínez-Martínez
authors: Silvia
authors: S
authors: Montoro-García
authors: Francisco
authors: F
authors: García-Carmona
authors: Hideto
authors: H
authors: Takami
authors: Alvaro
authors: A
authors: Sánchez-Ferrer
mesh_terms: D000115:Acetylesterase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001407:Bacillus / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D002241:Carbohydrates / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011522:Protons; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D040681:Structural Homology, Protein; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D002241:Carbohydrates; D011522:Protons; D011994:Recombinant Proteins; C096859:rhamnogalacturonan acetylesterase; D000115:Acetylesterase