Complete genome sequence of the kirromycin producer Streptomyces collinus Tü 365 consisting of a linear chromosome and two linear plasmids.

Streptomyces collinus Tü 365 (DSMZ 40733), isolated from Kouroussa (Guinea), is the producer of the elfamycin family antibiotic kirromycin, which inhibits bacterial protein biosynthesis by interfering with elongation factor EF-Tu. Here, we report on the Streptomyces collinus Tü 365 complete genome sequence of the 8.27 MB chromosome and the two plasmids SCO1 and SCO2.

The AT₂ domain of KirCI loads malonyl extender units to the ACPs of the kirromycin PKS.

The antibiotic kirromycin is assembled by a hybrid modular polyketide synthases (PKSs)/nonribosomal peptide synthetases (NRPSs). Five of six PKSs of this complex assembly line do not have acyltransferase (AT) and have to recruit this activity from discrete AT enzymes. Here, we show that KirCI is a discrete AT which is involved in kirromycin production and displays a rarely found three-domain architecture (AT₁-AT₂-ER).

The phosphopantetheinyl transferase KirP activates the ACP and PCP domains of the kirromycin NRPS/PKS of Streptomyces collinus Tü 365.

The main steps in the biosynthesis of complex secondary metabolites such as the antibiotic kirromycin are catalyzed by modular polyketide synthases (PKS) and/or nonribosomal peptide synthetases (NRPS). During antibiotic assembly, the biosynthetic intermediates are attached to carrier protein domains of these megaenzymes via a phosphopantetheinyl arm. This functional group of the carrier proteins is attached post-translationally by a phosphopantetheinyl transferase (PPTase).