A gene (bar) was identified adjacent to the hrdD sigma factor gene in Streptomyces coelicolor A3(2). The predicted bar product showed 32.2% and 30.4% identity to those of the pat and bar genes of the bialaphos (Bp) producers Streptomyces viridochromogenes and Streptomyces hygroscopicus, respectively; these genes encode phosphinothricin (PPT) N-acetyltransferases that function as enzymes in the Bp biosynthetic pathway and as resistance determinants. The S. coelicolor bar gene conferred high-level resistance to Bp when cloned in S. coelicolor on a high-copy-number vector. Enzymic assay showed that the S. coelicolor bar gene product inactivates PPT by transfer of acetyl groups from acetyl CoA. The S. coelicolor bar gene appears to be expressed from two promoters (p1 and p2) and is divergently transcribed with respect to hrdD. The downstream (barp2) transcript overlaps the hrdDp1 transcript and the upstream (barp1) transcript overlaps both the hrdDp1 and hrdDp2 transcripts. Inactivation of hrdD did not prevent transcription from either bar promoter, indicating that sigma hrdD is not essential for recognition of these sequences.
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http://dx.doi.org/10.1016/0378-1119(91)90462-k | DOI Listing |
Microb Cell Fact
November 2022
Department of Pharmaceutical Biology, Eberhard-Karls University Tübingen, Auf der Morgenstelle 8, 72076, Tübingen, Germany.
Background: Caprazamycins are liponucleoside antibiotics showing bioactivity against Gram-positive bacteria including clinically relevant Mycobacterium tuberculosis by targeting the bacterial MraY-translocase. Their chemical structure contains a unique 3-methylglutaryl moiety which they only share with the closely related liposidomycins. Although the biosynthesis of caprazamycin is understood to some extent, the origin of 3-methylglutaryl-CoA for caprazamycin biosynthesis remains elusive.
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February 1995
Department of Ecology, Genetics and Microbiology, Faculty of Biology, University of León, Spain.
Three genes (hrd) homologous to the rpoD gene of Escherichia coli, that encode sigma factor-like proteins, have been cloned from DNA of the candicidin-producing strain Streptomyces griseus IMRU 3570. They are located in different regions of the chromosome. Sequence analysis showed that the first one is analogous to the hrdB gene of S.
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July 1991
School of Biological Sciences, University of East Anglia, University Plain, Norwich, U.K.
A gene (bar) was identified adjacent to the hrdD sigma factor gene in Streptomyces coelicolor A3(2). The predicted bar product showed 32.2% and 30.
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