Genomic and proteomic exploration of regulatory pathways in antibiotic producing Streptomyces.

摘要

Streptomyces spp. constitute some of the most prolific producers of naturally occurring therapeutic molecules that are in common clinical use today. These organisms belong to a class of saprophytic soil-dwelling filamentous bacteria that exhibit a remarkably complex life cycle. Although significant progress has been made in the past five decades, details elucidating the pathways that regulate biosynthesis of these secondary metabolites remain sketchy. With the aid of genomic and proteomic tools, it is now possible to explore the dynamics of thousands of genes in a single experiment.; In this work, whole-genome DNA microarrays were employed to probe the effects of mutations in several known or potentially important regulatory proteins in Streptomyces coelicolor. Among them, transcriptome profiling of a mutant in AfsS, a small antibiotic regulatory protein, enabled the identification of hitherto unknown links between nutritional starvation response and antibiotic production. Also, comparative genomic analysis with S. lividans, a close but usually antibiotic non-producing relative of S. coelicolor, identified genomic segments of S. coelicolor that may potentially encode factors regulating secondary metabolite synthesis. In a complementary approach, proteomic profiling of growth phase dependent gene expression was carried out. The analysis revealed that post-transcriptional regulatory mechanisms were quite prominent in Streptomyces and that these mechanisms sometimes act in a concerted fashion among functionally related genes. As a means to investigate these mechanisms, metabolic labeling of proteins followed by quantitative mass spectrometry using iTRAQ analysis was carried out to explore the diversity among protein degradation rates. Together, these analyses should provide some important clues leading to future experiments that can elucidate gene regulation in streptomycetes.