Identification of truncated form of NosP as a transcription factor to regulate the biosynthesis of nosiheptide.

Nosiheptide (NOS), a typical member of the thiopeptides, possesses strong activities against multidrug-resistant, gram-positive bacterial pathogens. Similar to other thiopeptides, the biosynthetic pathway of NOS belongs to a ribosomally synthesized and posttranslationally modified peptide system. Bioinformatics analysis of the NOS gene cluster suggests that nosP gene encodes a homologous protein of the Streptomyces antibiotic regulatory protein (SARP) family. In the present study, the actual initiation codon of nosP was identified by comparison of potential initiation codons GUG and AUG. In contrast to previous predictions of starting with GUG, AUG, corresponding to methionine residue as the 53rd residue in the original sequence, is actually the initiation codon of nosP, indicating that a truncated form of NosP (NosP53-323) is a functional protein. For better understanding of the transcriptional regulation for NOS biosynthesis, the binding region was subsequently investigated with NosP53-323, demonstrating that NosP53-323 specifically binds the bidirectional nosL-nosM promoter region. Additionally, NosP53-323 was confirmed to serve as a transcription factor to activate the transcription of all 15 structural genes in the gene cluster. The present study provides new insights into pathway-specific regulation of the biosynthesis of NOS, which would be beneficial to the investigation of the regulatory function of similar SARP proteins in the gene clusters of other thiopeptides.-Wu, X., Jin, L., Zhang, H., Tong, R., Ma, M., Chen, Y. Identification of truncated form of NosP as a transcription factor to regulate the biosynthesis of nosiheptide. © FASEB.