Regulatory Patterns of Crp on Monensin Biosynthesis in Streptomyces cinnamonensis

Abstract

Monensin, produced by Streptomyces cinnamonensis, is a polyether ionophore antibiotic widely used as a coccidiostat and a growth-promoting agent in agricultural industry. In this study, cyclic AMP receptor protein (Crp), the global transcription factor for regulation of monensin biosynthesis, was deciphered. The overexpression and antisense RNA silencing of crp revealed that Crp plays a positive role in monensin biosynthesis. RNA sequencing analysis indicated that Crp exhibited extensive regulatory effects on genes involved in both primary metabolic pathways and the monensin biosynthetic gene cluster (mon). The primary metabolic genes, including acs, pckA, accB, acdH, atoB, mutB, epi and ccr, which are pivotal in the biosynthesis of monensin precursors malonyl-CoA, methylmalonyl-CoA and ethylmalonyl-CoA, are transcriptionally upregulated by Crp. Furthermore, Crp upregulates the expression of most mon genes, including all PKS genes (monAI to monAVIII), tailoring genes (monBI-monBII-monCI, monD and monAX) and a pathway-specific regulatory gene (monRI). Enhanced precursor supply and the upregulated expression of mon cluser by Crp would allow the higher production of monensin in S. cinnamonensis. This study gives a more comprehensive understanding of the global regulator Crp and extends the knowledge of Crp regulatory mechanism in Streptomyces.

Comparative Transcriptome Analysis Demonstrates the Positive Effect of the Cyclic AMP Receptor Protein Crp on Daptomycin Biosynthesis in Streptomyces roseosporus

“…Crp deficiency retards growth, which is consistent with the phenotype of the adenylate cyclase (cya) mutant that cannot synthesize cAMP (Derouaux et al, 2004b). In addition to morphological development, recent studies have demonstrated that Crp regulates the synthesis of a range of secondary metabolites, such as actinomycin (Act), undecylprodigiosin (Red), and calcium-dependent antibiotic (CDA) in S. coelicolor (Gao et al, 2012), and monensin in Streptomyces cinnamonensis, by enhancing acyl-CoA precursors and upregulating the transcription of biosynthetic gene clusters (Lin et al, 2020).…”

“…The global regulator Crp protein regulates not only the core genes of the secondary metabolite biosynthetic gene cluster, but also the cluster-situated regulatory gene (monRI) in S. cinnamonensis (Lin et al, 2020). In S. roseosporus, dptR1, dptR2, and dptR3 are located adjacent to the dpt gene cluster, which leads to their description as potential cluster-situated regulators (Miao et al, 2005).…”

“…The transcriptional regulatory mechanism of the Crp-cAMP complex in E. coli has been thoroughly elucidated (Gosset et al, 2004). In both E. coli and Streptomyces, the homologous sequence for Crp has been identified (Angell et al, 1994;Derouaux et al, 2004a;Lin et al, 2020). The protein structure of Crp (PDB: 1HW5) has also been clearly identified in E. coli-derived bacteria (Won et al, 2009).…”

Systems and synthetic biology to elucidate secondary metabolite biosynthetic gene clusters encoded inStreptomycesgenomes

“…Through this approach, a regulon of 12 transcriptional regulators of Streptomyces has been elucidated to date, including MtrA, 122 PhoU, 125 LmbU, 129 and Crp. 128 For instance, LmbU is a transcriptional regulator encoded in the lincomycin BGC of S. lincolnensis known as a pathway-specific regulator, that positively controls lincomycin production. Indeed, the lmbU deletion strain completely lost its lincomycin production ability.…”

Synthetic biology approaches to actinomycete strain improvement

“… 2015a ) and to elucidate the regulatory role of the cyclic AMP receptor protein (Crp) in Streptomyces cinnamonensis by comparing the monensin yields and transcriptomic profiles between control, crp -overexpressing and crp -silencing strains (Lin et al . 2020 ). There is a pressing need for more extensive studies to identify sRNAs and elucidate their function in Streptomyces and other actinomycetes with a rich secondary metabolism.…”