Discovery and Bioactivity of the Novel Lasso Peptide Microcin Y

Abstract

Lasso peptides, a class of ribosomally synthesized and post-translationally modified peptides (RiPPs) secreted by bacteria, have antimicrobial activity. Here, a novel lasso peptide, microcin Y (MccY), was discovered and characterized. The gene cluster for MccY synthesis was cloned for expression in Escherichia coli. This peptide was purified by HPLC and characterized by Q-TOF. MIC assays showed that some Bacillus, Staphylococcus, Pseudomonas, Shigella, and Salmonella strains were sensitive to MccY. Interestingly, Salmonellatyphimurium and Salmonella infantis were efficiently inhibited by MccY, while they were not affected by MccJ25, a lasso peptide that has antibacterial effects on many Salmonella strains. Furthermore, MccY-resistant strains of S. typhimurium were screened, and mutations were found in FhuA and SbmA, indicating the importance of these transporters for MccY absorption. This novel peptide can greatly broaden the antimicrobial spectrum of MccJ25 in Salmonella and is expected to be used in food preservation and animal feed additive areas.

The Anti-Burkholderia Lasso Peptide Ubonodin Co-Opts the Siderophore Receptor PupB for Cellular Entry

“…The bioactivity of ubonodin, and indeed any compound with an intracellular target, is a product of its ability to first access and then bind its target. Previous studies have shown that cellular uptake is required for lasso peptides with RNAP-inhibiting activity to be bioactive (Cheung-Lee et al, 2019; Li et al, 2021; Metelev et al, 2017; Salomón and Farías, 1993). In all cases where the lasso peptide OM receptor has been identified, the receptors are TonB-dependent transporters (TBDTs), a ubiquitous class of bacterial OM proteins that import essential trace nutrients like iron from the environment ( Figure 3A ) (Krewulak and Vogel, 2011; Noinaj et al, 2010).…”

“…Microcin J25 uses the E. coli TBDT FhuA for OM transport (Mathavan et al, 2014; Salomón and Farías, 1993). Klebsidin (Metelev et al, 2017) and microcin Y (Li et al, 2021) likewise use FhuA-like transporters. In these cases where the OM transporters were identified, the ability to readily isolate resistant mutants that have a mutation in the OM transporter or to predict a close homolog to E. coli FhuA was crucial to their identification.…”

Microcins reveal natural mechanisms of bacterial manipulation to inform therapeutic development

“…Many of these features have been reviewed [65], but will be described briefly here. Uptake is achieved through the FhuA [115,116] or OmpF [65,117] receptors.…”

“…For the only Class I microcin where the energetic means of uptake is known, MccJ25, the TonB-ExbBD system is used [107]. Identified inner membrane receptors are the transporters, SbmA [107, 116, 117] or YejABEF (ABC transporter) [118]. SbmA belongs to a proposed new class of secondary transporter [119].…”

“…The ecological roles of microcins are not well elucidated, as too few ecologically relevant studies of microcin function have been conducted. Most studies are in vitro examinations of a single microcin-producing strain or purified microcin with a single target strain per assay, designed with the goal of demonstrating antimicrobial activity [91,116,146]. In vitro explorations of in vivo phenomena can be misleading; just because a bacteriocin is antimicrobial in high concentrations in vitro does not mean it has the same ecological function [12,166].…”