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J. Bacteriol., 03 1995, 1208-1215, Vol 177, No. 5
K Madduri and CR Hutchinson
We previously proposed that the adjacent dnrIJ genes represent a two-
component regulatory system controlling daunorubicin biosynthesis in
Streptomyces peucetius on the basis of the homology of the DnrI and DnrJ
proteins to other response regulator proteins and the effect of a
dnrI::aphII mutation. In the present paper we report the results of work
with the dnrI::aphII mutant in complementation, bioconversion, and
transcriptional analysis experiments to understand the function of dnrI.
For five putative operons in the sequenced portion of the S. peucetius
daunorubicin biosynthesis gene cluster examined, all of the potential
transcripts are present in the delta dnrJ mutant and wild- type strains but
absent in the dnrI::aphII strain. Since these transcripts code for both
early- and late-acting enzymes in daunorubicin biosynthesis, dnrI seems to
control all of the daunorubicin biosynthesis genes directly or indirectly.
Transcriptional mapping of the 5' and 3' ends of the dnrIJ transcript and
the termination site of the convergently transcribed dnrZUV transcript
reveals, interestingly, that the two transcripts share extensive
complementarity in the regions coding for daunorubicin biosynthesis
enzymes. In addition, dnrI may regulate the expression of the drrAB and
drrC daunorubicin resistance genes. The delta dnrJ mutant accumulates
epsilon-rhodomycinone, the aglycone precursor of daunorubicin. Since this
mutant contains transcripts coding for several early- and late- acting
enzymes and since dnr mutants blocked in deoxysugar biosynthesis accumulate
epsilon-rhodomycinone, we conclude that dnrJ is a daunosamine biosynthesis
gene.(ABSTRACT TRUNCATED AT 250 WORDS)
Copyright © 1995, American Society for Microbiology
Functional characterization and transcriptional analysis of the dnrR1 locus, which controls daunorubicin biosynthesis in Streptomyces peucetius
School of Pharmacy, University of Wisconsin, Madison 53706.
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