An investigation of Crp function in the development and secondary metabolism of Streptomyces coelicolor

Abstract

<p>Cyclic AMP receptor protein (Crp) is a transcription regulator controlling diverse cellular processes in many bacteria. Deletion of the <em>crp </em>gene of <em>Streptomyces coelicolor</em> significantly delays spore germination but accelerates sporulation, while overexpression of <em>crp</em> arrests morphological development at the vegetative stage. In this study, I set out to dissect Crp function during spore formation and germination by manipulating its expression at different developmental stages using a strain carrying the <em>crp</em> gene cloned downstream of a thiostrepton inducible promoter (<em>tipA-crp</em>). The impact of Crp on the synthesis of actinorhodin, undecylprodigiosin and calcium-dependent antibiotic was assessed by performing quantitative antibiotic production assays. Chromatin immunoprecipitation-microarray assays were applied to uncover ~ 400 Crp association sites distributed across the entire genome of <em>S. coelicolor</em>. Genes associated with these sites are involved in a remarkable variety of functions including metabolism, morphogenesis and transcription regulation, with secondary metabolism clearly overrepresented. This result correlates with our transcriptional profiling experiments, which revealed that the majority of the genes affected by Crp induction fall in the functional categories of secondary metabolism, morphogenesis and transcription factors, amongst which the most striking ones are those located in the antibiotic biosynthetic clusters: <em>act</em>, <em>red</em>, <em>cda</em>, and <em>cpk</em>. Finally, multiple <em>Streptomyces</em> species have been engineered to overproduce Crp and have been subjected to comparative metabolic profiling to identify the up- and down-regulation of secondary metabolite production elicited by Crp overexpression.</p>