title: A novel beta-peptidyl aminopeptidase (BapA) from strain 3-2W4 cleaves peptide bonds of synthetic beta-tri- and beta-dipeptides.
abstract: A novel bacterial strain that was capable of growing on the beta-tripeptide H-betahVal-betahAla-betahLeu-OH as the sole carbon and nitrogen source was isolated from an enrichment culture. On the basis of physiological characterization, partial 16S rRNA sequencing, and fatty acid analysis, strain 3-2W4 was identified as a member of the family Sphingomonadaceae. Growth on the beta-tripeptide and the beta-dipeptide H-betahAla-betahLeu-OH was observed, and emerging metabolites were characterized. Small amounts of a persisting metabolite, the N-acetylated beta-dipeptide, were identified in both media. According to dissolved organic carbon measurements, 74 to 80% of the available carbon was dissimilated. The beta-peptide-degrading enzyme was purified from the crude cell extract of cells from strain 3-2W4 grown on complex medium. The enzyme was composed of two subunits, and the N-terminal sequences of both were determined. With this information, it was possible to identify the complete nucleotide sequence and to deduce the primary structure of the gene bapA. The gene encoded a beta-peptidyl aminopeptidase (BapA) of 402 amino acids that was synthesized as preprotein with a signal sequence of 29 amino acids. The enzyme was cleaved into two subunits (residues 30 to 278 and 279 to 402). It belonged to the N-terminal nucleophile (Ntn) hydrolase superfamily.
authors.affiliation: Swiss Federal Institute of Environmental Science and Technology (EAWAG), Uberlandstrasse 133, CH-8600 Dübendorf, Switzerland. kohler@eawag.ch.
authors.forename: Birgit
authors.initials: B
authors.lastname: Geueke
authors.forename: Kenji
authors.initials: K
authors.lastname: Namoto
authors.forename: Dieter
authors.initials: D
authors.lastname: Seebach
authors.forename: Hans-Peter E
authors.initials: HP
authors.lastname: Kohler
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003470:Culture Media; D017931:DNA Primers; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D042301:Sphingomonadaceae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D003470:Culture Media; D017931:DNA Primers; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases