Functional Genome Mining Reveals a Class V Lanthipeptide Containing a d‐Amino Acid Introduced by an F₄₂₀H₂‐Dependent Reductase

Abstract

Lantibiotics are a type of ribosomally synthesized and post‐translationally modified peptides (termed lanthipeptides) with often potent antimicrobial activity. Herein, we report the discovery of a new lantibiotic, lexapeptide, using the library expression analysis system (LEXAS) approach. Lexapeptide has rare structural modifications, including N‐terminal (N,N)‐dimethyl phenylalanine, C‐terminal (2‐aminovinyl)‐3‐methyl‐cysteine, and d‐Ala. The characteristic lanthionine moiety in lexapeptide is formed by three proteins (LxmK, LxmX, and LxmY), which are distinct from enzymes known to be involved in lanthipeptide biosynthesis. Furthermore, a novel F420H2‐dependent reductase (LxmJ) from the lexapeptide biosynthetic gene cluster (BGC) is identified to catalyze the reduction of dehydroalanine to install d‐Ala. Our findings suggest that lexapeptide is the founding member of a new class of lanthipeptides that we designate as class V. We also identified further class V lanthipeptide BGCs in actinomycetes and cyanobacteria genomes, implying that other class V lantibiotics await discovery.

Self‐immunity to antibacterial peptides by ABC transporters

“…In 2013, a new and still commonly accepted classification was introduced based on the characteristics of the modification enzymes [1]. Recently, a new class was identified, which brings the number of different classes to five [17,18]. In class I, the enzymes needed for the modification are two single monofunctional enzymes where the dehydratase (LanB) and the cyclase (LanC) are forming a complex in the cell.…”

Formation of an Aminovinyl-Cysteine Residue in Thioviridamide Non-Lanthipeptides Occurs through a Path Independent of Known Lanthionine Synthetase Activity inStreptomyces sp. NRRL S-87

“…Recently, Tao et al identified lexapeptide, a new RiPP containing both Lan and AviCys thioether residues, and the associated biosynthetic gene cluster in S. rochei Sal35. 16 Using a similar heterologous co-expression method in E. coli, four dedicated PTM enzymes, i.e., LxmKYXD, were indicated to be necessary for the formation of the AviCys residue in lexapeptide. Remarkably, despite poor homology in primary sequence, secondary structure prediction revealed that LxmKYXD are the counterparts of TvaCDEFS-87 in this study.…”

“…The counterparts of TvaFS-87 were known in the biosynthesis of various AviCys-containing RiPPs. Either as a LanD protein (for lanthipeptides [10][11][12]15 ) or as a LanD-like protein (for non-lanthipeptides 6,8,16 ), these flavoproteins share the oxidative decarboxylation activity necessary for AviCys formation and can process the C-terminal Cys residue of a precursor peptide to an enethiol before Michael addition to the upstream Dha/Dhb residue. The homologs of TvaCS-87 and TvaES-87 were previously annotated as hypothetic proteins, with the exception in ref.…”

Combating Antimicrobial Resistance With New-To-Nature Lanthipeptides Created by Genetic Code Expansion

“…classified based on the biosynthetic mechanisms involved in their structural maturation, the recently discovered modified peptides, including Cocaoidin and Lexapeptide, exhibited novel modification features such as different biosynthetic gene clusters and have been introduced as class V lanthipeptides (Ortiz-López et al, 2020;Xu et al, 2020).…”