Synergistic Binding of the Leader and Core Peptides by the Lantibiotic Synthetase HalM2

Abstract

Lanthipeptides are a class of ribosomally-produced and post-translationally modified peptides (RiPPs) that possess a variety of biological activities, but typically act as antimicrobial agents (lantibiotics). Haloduracin is a lantibiotic that is composed of two post-translationally modified peptides, Halα and Halβ, which are biosynthesized from the precursor peptides HalA1 and HalA2 by their cognate lanthipeptide synthetases, HalM1 and HalM2, respectively. Co-expression studies of HalM1 and HalM2 with chimeric peptides consisting of the leader peptide of HalA1 and the core peptide of HalA2 (or vice versa) showed that the synthetases require both the cognate leader and core peptides for efficient processing. Investigation of the affinity in vitro showed that binding of the N-terminal leader peptide by HalM2 increases its affinity for the C-terminal core peptide. Thus, the two segments of the precursor peptide HalA2 synergistically bind to HalM2.

The enterococcal cytolysin synthetase has an unanticipated lipid kinase fold

“…The immediacy of the phosphorylation and phosphate-elimination sites allows for both reactions to occur in a processive manner to yield the dehydroamino residue, which can then be consigned to the cyclization domain for subsequent Michael-type addition reaction. The ordered activation loop in CylM precludes the need for an activation-induced conformational change, observed for other lipid kinases, as binding of the substrate is dictated largely by the leader sequence ( Abts et al, 2013 ; Thibodeaux et al, 2015 ). The structure of the CylM protein now allows installation of probes to monitor the movement of the substrates between the two active sites in LanM proteins to better understand the substantial motions of the substrate peptides during catalysis ( Thibodeaux et al, 2014 ).…”

New Insights into the Biosynthetic Logic of Ribosomally Synthesized and Post-translationally Modified Peptide Natural Products

“…However, the observed enzymatic activity in the absence of a leader peptide can only be explained if the RiPP biosynthetic machinery recognizes to some extent the core peptide. Indeed, recent fluorescence polarization assays revealed synergistic binding of the HalA2 leader sequence and core peptide by its cognate class II lanthionine synthetase HalM2 (Thibodeaux et al, 2015). These results are consistent with a model where leader peptide binding induces a conformational change in the enzyme that increases its affinity for the core peptide.…”

Structural Characterization and Bioactivity Analysis of the Two-Component Lantibiotic Flv System from a Ruminant Bacterium

“…The inability of FlvM1 to modify FlvA2.a and 2.g and FlvM2 to modify FlvA1.a suggests a high degree of substrate selectivity that is probably governed by recognition of the different leader peptides (Fig. 1B) (Thibodeaux et al, 2015; Yang and van der Donk, 2013). …”