Affiliation:
1. Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E9
Abstract
ABSTRACT
A polycistronic transcript that is initiated at the
lat
promoter has been implicated in the expression of the genes involved in early steps of cephamycin C biosynthesis in
Streptomyces clavuligerus. pcbC
is also expressed as a monocistronic transcript from its own promoter. However, an alternative interpretation involving expression via three separate yet interdependent transcripts has also been proposed. To distinguish between these possibilities, mutants lacking the
lat
promoter and containing a transcription terminator within the
lat
gene (Δ
lat
::
tsr
/term mutants) were created. This mutation eliminated the production of lysine-ɛ-aminotransferase (the
lat
gene product) but also affected the expression of downstream genes, indicating an operon arrangement. Production of δ-(
l
-α-aminoadipyl)-
l
-cysteinyl-
d
-valine synthetase (ACVS) (the
pcbAB
gene product) was eliminated in Δ
lat
::
tsr
/term mutants, while production of isopenicillin N synthase (IPNS) (the
pcbC
gene product) was greatly reduced. The provision of α-aminoadipate to the Δ
lat
::
tsr
/term mutants, either via exogenous feeding or via
lat
gene complementation, did not restore production of ACVS or IPNS. Analysis of RNA isolated from the Δ
lat
::
tsr
/term mutants confirmed that the polycistronic transcript was absent but also indicated that monocistronic
pcbC
transcript levels were greatly decreased. In contrast, Δ
lat
mutants created by in-frame internal deletion of
lat
maintained the polycistronic transcript and allowed production of wild-type levels of both ACVS and IPNS.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
13 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献