title: Cloning and expression analysis of the pcbAB-pcbC beta-lactam genes in the marine fungus Kallichroma tethys.
abstract: Here we report the identification of the beta-lactam biosynthesis genes pcbAB and pcbC from a cosmid genomic DNA library of the marine fungus Kallichroma tethys. A BLAST homology search showed that they share high sequence identity with the delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine (ACV) synthetases and isopenicillin N synthases, respectively, of various fungal and bacterial beta-lactam producers, while phylogenetic analysis indicated a close relationship with homologous genes of the cephalosporin-producing pyrenomycete Acremonium chrysogenum. Expression analysis by reverse transcription-PCR suggested that both genes are highly regulated and are expressed in the late growth phase of K. tethys cultures. Complementation of an Aspergillus nidulans strain deficient in ACV synthetase suggested that at least pcbAB is functional, although attempts to isolate active antibiotic from K. tethys were unsuccessful.
authors.affiliation: Department of Biology and Chemistry, City University of Hong Kong, Kowloon Tong, Hong Kong Special Administrative Region, People's Republic of China.
authors.forename: Chi-Fai
authors.initials: CF
authors.lastname: Kim
authors.forename: Simon K Y
authors.initials: SK
authors.lastname: Lee
authors.forename: Jackie
authors.initials: J
authors.lastname: Price
authors.forename: Ralph W
authors.initials: RW
authors.lastname: Jack
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Turner
authors.forename: Richard Y C
authors.initials: RY
authors.lastname: Kong
mesh_terms: D001483:Base Sequence; D003001:Cloning, Molecular; D003470:Culture Media; D015966:Gene Expression Regulation, Fungal; D006999:Hypocreales / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D010453:Peptide Synthases / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D011401:Promoter Regions, Genetic; D012623:Seawater / Q000382:microbiology*; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic; D047090:beta-Lactams / Q000378:metabolism*
chemical_list: D003470:Culture Media; D047090:beta-Lactams; D010088:Oxidoreductases; C038370:isopenicillin N synthetase; D010453:Peptide Synthases; C095368:alpha-aminoadipyl-cysteinyl-valine synthetase