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Antimicrobial Agents and Chemotherapy, March 2000, p. 720-726, Vol. 44, No. 3
Department of Biological Sciences, University
of Alberta, Edmonton, Alberta, Canada T6G 2E9
Received 6 July 1999/Returned for modification 27 October
1999/Accepted 16 December 1999
Genes encoding the proteins required for clavulanic acid
biosynthesis and for cephamycin biosynthesis are grouped into a
"supercluster" in Streptomyces clavuligerus. Nine open
reading frames (ORFs) associated with clavulanic acid biosynthesis were
located in a 15-kb segment of the supercluster, including six ORFs
encoding known biosynthetic enzymes or regulatory proteins, two ORFs
that have been reported previously but whose involvement in clavulanic acid biosynthesis is unclear, and one ORF not previously reported. Evidence for the involvement of these ORFs in clavulanic acid production was obtained by generating mutants and showing that all were
defective for clavulanic acid production when grown on starch
asparagine medium. However, when five of the nine mutants, including
mutants defective in known clavulanic acid biosynthetic enzymes, were
grown in a soy-based medium, clavulanic acid-producing ability was
restored. This ability to produce clavulanic acid when seemingly
essential biosynthetic enzymes have been mutated suggests that
paralogous genes encoding functionally equivalent proteins exist for
each of the five genes but that these paralogues are expressed only in
the soy-based medium. The five genes that have paralogues encode
proteins involved in the early steps of the pathway common to the
biosynthesis of both clavulanic acid and the other clavam metabolites
produced by this organism. No evidence was seen for paralogues of the
four remaining genes involved in late, clavulanic acid-specific steps
in the pathway.
0066-4804/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Enzymes Catalyzing the Early Steps of Clavulanic Acid
Biosynthesis Are Encoded by Two Sets of Paralogous Genes in
Streptomyces clavuligerus
*
Corresponding author. Mailing address: Department of
Biological Sciences, CW-405 Biological Sciences Building, University of
Alberta, Edmonton, Alberta T6G 2E9, Canada. Phone: (780) 492-0672. Fax:
(780) 492-2216. E-mail: susan.jensen{at}ualberta.ca.
Present address: Diversa Corporation, San Diego, CA 92121.
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