Lacticin 481 Synthetase Phosphorylates its Substrate during Lantibiotic Production

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244

Lanthionine-containing peptides (lanthipeptides) are a family of ribosomally synthesized and posttranslationally modified peptides containing (methyl)lanthionine residues. Here we present a phylogenomic study of the four currently known classes of lanthipeptide synthetases (LanB and LanC for class I, LanM for class II, LanKC for class III, and LanL for class IV). Although they possess very similar cyclase domains, class II-IV synthetases have evolved independently, and LanB and LanC enzymes appear to not always have coevolved. LanM enzymes from various phyla that have three cysteines ligated to a zinc ion (as opposed to the more common CysCys-His ligand set) cluster together. Most importantly, the phylogenomic data suggest that for some scaffolds, the ring topology of the final lanthipeptides may be determined in part by the sequence of the precursor peptides and not just by the biosynthetic enzymes. This notion was supported by studies with two chimeric peptides, suggesting that the nisin and prochlorosin biosynthetic enzymes can produce the correct ring topologies of epilancin 15X and lacticin 481, respectively. These results highlight the potential of lanthipeptide synthetases for bioengineering and combinatorial biosynthesis. Our study also demonstrates unexplored areas of sequence space that may be fruitful for genome mining. molecular evolution | natural products | phylogeny | posttranslational modification | lantibiotics

Section: Resultsmentioning

confidence: 99%

Evolution of lanthipeptide synthetases

Zhang

Velásquez

et al. 2012

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175

244

“…Purified HalA1 and HalA2 were incubated together with purified HalM1 and HalM2 in an assay mixture containing TCEP [Tris(2-carboxyethyl)phosphine hydrochloride], MgCl 2 , and ATP (6,20) and then subjected to MALDI-MS. Incubation of the prepeptides with both modification enzymes resulted in the 3-fold dehydration of HalA1 and the 7-fold dehydration of HalA2 (Fig. 2).…”

Section: Resultsmentioning

confidence: 99%

Discovery and in vitro biosynthesis of haloduracin, a two-component lantibiotic

McClerren¹,

Cooper

Quan

et al. 2006

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321

Lantibiotics are ribosomally synthesized peptides that undergo posttranslational modifications to their mature, antimicrobial form. They are characterized by the unique amino acids lanthionine and methyllanthionine, introduced by means of dehydration of Ser͞Thr residues followed by reaction of the resulting dehydro amino acids with cysteines to form thioether linkages. Two-component lantibiotics use two peptides that are each posttranslationally modified to yield two functionally distinct products that act in synergy to provide bactericidal activity. By using genetic data instead of isolation, a two-component lantibiotic, haloduracin, was identified in the genome of the Gram-positive alkaliphilic bacterium Bacillus halodurans C-125. We show that heterologously expressed and purified precursor peptides HalA1 and HalA2 are processed by the purified modification enzymes HalM1 and HalM2 in an in vitro reconstitution of the biosynthesis of a two-component lantibiotic. The activity of each HalM enzyme is substratespecific, and the assay products exhibit antimicrobial activity after removal of their leader sequences at an engineered Factor Xa cleavage site, indicating that correct thioether formation has occurred. Haloduracin's biological activity depends on the presence of both modified peptides. The structures of the two mature haloduracin peptides Hal␣ and Hal␤ were investigated, indicating that they have similarities as well as some distinct differences compared with other two-component lantibiotics.lanthionine ͉ dehydroalanine ͉ antibiotic

“…The leader peptide binding site has been previously shown to not be located in this C-terminal domain (25). The proposed activation mechanism for LanB dehydratases stands in contrast to the activation of the hydroxyl groups of Ser and Thr by phosphorylation during the dehydration process of classes II, III, and IV lanthipeptides (6,7,29). Why glutamylation of Ser/Thr would evolve as an alternative means of Ser/Thr activation is unclear.…”

Section: Discussionmentioning

confidence: 95%

In vitro activity of the nisin dehydratase NisB

Garg¹,

Salazar-Ocampo

Donk

2013

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111

167

The biosynthesis of several classes of ribosomally synthesized and posttranslationally modified peptides involves dehydration of serine and threonine residues. For class I lantibiotics, thiopeptides, and goadsporin, this dehydration is catalyzed by lanthionine biosynthetic enzyme B (LanB) or LanB-like proteins. Although LanB proteins have been studied since 1992, in vitro reconstitution of their dehydration activity has been elusive. We show here the in vitro activity of the dehydratase involved in the biosynthesis of the food preservative nisin (NisB). In vitro, NisB dehydrated its substrate peptide NisA eight times in the presence of glutamate, ATP, Mg 2+ , and the ribosomal/ membrane fraction of bacterial cell extract. Mutation of 23 highly conserved residues of NisB identified a number of amino acids that are essential for dehydration activity. In addition, these mutagenesis studies identified three mutants, R786A, R826A, and H961A, that result in multiple glutamylations of the NisA substrate. Glutamylation was observed during both Escherichia coli coexpression of NisA with these mutants and in vitro assays. Treatment of the glutamylated substrate with WT NisB results in dehydrated NisA, suggesting that the glutamylated peptide is an intermediate in dehydration. Collectively, these studies suggest that dehydration involves glutamylation of the side chains of Ser and Thr followed by elimination. The latter step has precedent in the virginiamycin resistance protein virginiamycin B lyase. These studies will facilitate investigation of other LanB proteins involved in the biosynthesis of lantibiotics, thiopeptides, and goadsporin.