Abstract
Comparative genome analysis revealed seven uncharacterized genes, sven0909 to sven0915, adjacent to the previously identified chloramphenicol biosynthetic gene cluster (sven0916–sven0928) of Streptomyces venezuelae strain ATCC 10712 that was absent in a closely related Streptomyces strain that does not produce chloramphenicol. Transcriptional analysis suggested that three of these genes might be involved in chloramphenicol production, a prediction confirmed by the construction of deletion mutants. These three genes encode a cluster-associated transcriptional activator (Sven0913), a phosphopantetheinyl transferase (Sven0914), and a Na+/H+ antiporter (Sven0915). Bioinformatic analysis also revealed the presence of a previously undetected gene, sven0925, embedded within the chloramphenicol biosynthetic gene cluster that appears to encode an acyl carrier protein, bringing the number of new genes likely to be involved in chloramphenicol production to four. Microarray experiments and synteny comparisons also suggest that sven0929 is part of the biosynthetic gene cluster. This has allowed us to propose an updated and revised version of the chloramphenicol biosynthetic pathway.
Highlights
Comparative genome analysis revealed seven uncharacterized genes, sven0909 to sven0915, adjacent to the previously identified chloramphenicol biosynthetic gene cluster of Streptomyces venezuelae strain ATCC 10712 that was absent in a closely related Streptomyces strain that does not produce chloramphenicol
The alignment of the Streptomyces sp. strain OH-4156 Solexa contigs on the S. venezuelae genome sequence in the region of the CHL biosynthetic gene cluster revealed the presence of seven genes adjacent to the previously identified CHL biosynthetic gene cluster that were absent in the nonproducing strain (Fig. 1A)
To gain insight into whether any of these newly identified genes might play a role in CHL production, we compared their transcriptional profiles with those of established CHL biosynthetic genes in the microarray data from submerged cultures of S. venezuelae and several of its developmental mutants that are deficient in sporulation
Summary
Comparative genome analysis revealed seven uncharacterized genes, sven0909 to sven0915, adjacent to the previously identified chloramphenicol biosynthetic gene cluster (sven0916–sven0928) of Streptomyces venezuelae strain ATCC 10712 that was absent in a closely related Streptomyces strain that does not produce chloramphenicol. Transcriptional analysis suggested that three of these genes might be involved in chloramphenicol production, a prediction confirmed by the construction of deletion mutants. These three genes encode a cluster-associated transcriptional activator (Sven0913), a phosphopantetheinyl transferase (Sven0914), and a Na؉/H؉ antiporter (Sven0915). Chloramphenicol (CHL) is a bacteriostatic antibiotic that inhibits protein synthesis by binding to the 50S subunit of the bacterial ribosome It is active against both Gram-negative and Gram-positive bacteria, including many multiply drug-resistant strains. By combining comparative genomics with microarray and bioinformatic analyses, we have identified four additional genes likely to be involved in CHL production, and we confirmed the participation of three of these in antibiotic biosynthesis by mutational analyses
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