title: A novel esterase subfamily with α/β-hydrolase fold suggested by structures of two bacterial enzymes homologous to L-homoserine O-acetyl transferases.
abstract: MekB from Pseudomonas veronii and CgHle from Corynebacteriumglutamicum belong to the superfamily of α/β-hydrolase fold proteins. Based on sequence comparisons, they are annotated as homoserine transacetylases in popular databases like UNIPROT, PFAM or ESTHER. However, experimentally, MekB and CgHle were shown to be esterases that hydrolyse preferentially acetic acid esters. We describe the x-ray structures of these enzymes solved to high resolution. The overall structures confirm the close relatedness to experimentally validated homoserine acetyl transferases, but simultaneously the structures exclude the ability of MekB and CgHle to bind homoserine and acetyl-CoA. Insofar the MekB and CgHle structures suggest dividing the homoserine transacetylase family into subfamilies, namely genuine acetyl transferases and acetyl esterases with MekB and CgHle as constituting members of the latter.
authors.affiliation: Department für Chemie, Institut für Biochemie, Universität zu Köln, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Tölzer
authors.affiliation: Department für Chemie, Institut für Biochemie, Universität zu Köln, Germany.
authors.forename: Sonia
authors.initials: S
authors.lastname: Pal
authors.affiliation: Institut für Industrielle Genetik, Universität Stuttgart, Germany.
authors.forename: Hildegard
authors.initials: H
authors.lastname: Watzlawick
authors.affiliation: Institut für Industrielle Genetik, Universität Stuttgart, Germany.
authors.forename: Josef
authors.initials: J
authors.lastname: Altenbuchner
authors.affiliation: Department für Chemie, Institut für Biochemie, Universität zu Köln, Germany.
authors.forename: Karsten
authors.initials: K
authors.lastname: Niefind
mesh_terms: D000105:Acetyl Coenzyme A / Q000737:chemistry / Q000378:metabolism; D000123:Acetyltransferases / Q000737:chemistry* / Q000145:classification / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D020134:Catalytic Domain; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D030562:Databases, Protein; D004950:Esterases / Q000737:chemistry* / Q000378:metabolism; D006714:Homoserine / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D011549:Pseudomonas / Q000201:enzymology*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D040681:Structural Homology, Protein; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D006714:Homoserine; D000105:Acetyl Coenzyme A; D000123:Acetyltransferases; C021369:homoserine O-acetyltransferase; D004950:Esterases
keywords: acetyl ester hydrolysis; crystal structure; esterase; l-homoserine O-transacetylase; methyl alkyl ketone degradation pathway; α/β-hydrolase fold