An unexpected role for the putative 4′-phosphopantetheinyl transferase-encoding genenysFin the regulation of nystatin biosynthesis inStreptomyces nourseiATCC 11455

Abstract

The nysF gene encoding a putative 4'-phosphopantetheinyl transferase (PPTase) is located at the 5' border of the nystatin biosynthesis gene cluster in Streptomyces noursei. PPTases carry out post-translational modification of the acyl carrier protein domains on the polyketide synthases (PKS) required for their full functionality, and hence NysF was assumed to be involved in similar modification of the nystatin PKS. At the same time, DNA sequence analysis of the genomic region adjacent to the nysF gene revealed a gene cluster for a putative lantibiotic biosynthesis. This finding created some uncertainty regarding which gene cluster nysF functionally belongs to. To resolve this ambiguity, nysF was inactivated by both insertion of a kanamycin (Km) resistance marker into its coding region, and by in-frame deletion. Surprisingly, the nystatin production in both the nysF::Km(R) and DeltanysF mutants increased by ca. 60% compared to the wild-type, suggesting a negative role of nysF in the nystatin biosynthesis. The expression of xylE reporter gene under control of different promoters from the nystatin gene cluster in the DeltanysF mutant was studied. The data obtained clearly show enhanced expression of xylE from the promoters of several structural and regulatory genes in the DeltanysF mutant, implying that NysF negatively regulates the nystatin biosynthesis.

The phosphopantetheinyl transferases: catalysis of a post-translational modification crucial for life

“…However, upon deletion of this gene, an increase in nystatin production was observed, suggesting a regulatory role for this protein. 54 Since nysF has not been characterized in more detail, it is unclear whether this protein is a bona fide PPTase, a regulatory gene product, or both.…”

Identification of functionally clustered nystatin-like biosynthetic genes in a rare actinomycetes, Pseudonocardia autotrophica

“…Downstream of nppG, a putative nppF gene whose 225 aa products are homologous to the 4Ј-phosphopantheteine transferases was identiWed. NppF is believed to carry out post-translational modiWcation of the ACP domains on the PKSs, which is required for their full functionality [5,36].…”

Exploration of geosmin synthase from Streptomyces peucetius ATCC 27952 by deletion of doxorubicin biosynthetic gene cluster

“…Occasionally, deletion of biosynthetic genes can lead to raise secondary metabolite production. Such was the case of nysF inactivation that increases nystatin production in S. noursei [31]. In the case of nanchangmycin production by S. nanchangensis, the production could be improved by selective deletion of other PKS-containing clusters found in the same organism.…”