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Diacylglycerol kinase is involved in regulation of expression of the lantibiotic mutacin II of Streptococcus mutans.

ABSTRACT: Genetic characterization of a Tn916 transposon mutant, Streptococcus mutans T8-1, defective in mutacin II production, revealed that the transposon was inserted into the 3' region of a diacylglycerol kinase (dgk) gene. The insertion occurred in the same region as described for another S. mutans mutant, GS5Tn1, which was altered in its ability to respond to environmental stress (Y. Yamashita, T. Takehara, and H. K. Kuramitsu, J. Bacteriol. 175:6220-6228, 1993). Quantitative primer extension from the mutacin structural gene mutA showed a decreased level (about eightfold) of mutA transcription for mutant T8-1. Mutacin production was restored by transforming mutant T8-1 with integration vector pVA891 containing an intact dgk gene. These data indicated that the full-length dgk gene product along with the mutacin biosynthetic operon are required for the production of the mutacin II lantibiotic.

SUBMITTER: Chen P

PROVIDER: S-EPMC106864 | biostudies-literature | 1998 Jan

REPOSITORIES: biostudies-literature

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Diacylglycerol kinase is involved in regulation of expression of the lantibiotic mutacin II of Streptococcus mutans.

Chen P P Novak J J Qi F F Caufield P W PW

Journal of bacteriology 19980101 1

Genetic characterization of a Tn916 transposon mutant, Streptococcus mutans T8-1, defective in mutacin II production, revealed that the transposon was inserted into the 3' region of a diacylglycerol kinase (dgk) gene. The insertion occurred in the same region as described for another S. mutans mutant, GS5Tn1, which was altered in its ability to respond to environmental stress (Y. Yamashita, T. Takehara, and H. K. Kuramitsu, J. Bacteriol. 175:6220-6228, 1993). Quantitative primer extension from t ...[more]

PMID: 9422608

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Project description:UnlabelledLantibiotics are ribosomally synthesized peptide antibiotics composed of an N-terminal leader peptide that is cleaved to yield the active antibacterial peptide. Significant advancements in molecular tools that promote the study of lantibiotic biosynthesis can be used in Streptococcus mutans. Herein, we further our understanding of leader peptide sequence and core peptide structural requirements for the biosynthesis and transport of the lantibiotic mutacin 1140. Our study on mutacin 1140 biosynthesis shows a dedicated secondary cleavage site within the leader peptide and the dependency of transport on core peptide posttranslational modifications (PTMs). The secondary cleavage site on the leader peptide is found at the -9 position, and secondary cleavage occurs before the core peptide is transported out of the cell. The coordinated cleavage at the -9 position was absent in a lanT deletion strain, suggesting that the core peptide interaction with the LanT transporter enables uniform cleavage at the -9 position. Following transport, the LanP protease was found to be tolerant to a wide variety of amino acid substitutions at the primary leader peptide cleavage site, with the exception of arginine at the -1 position. Several leader and core peptide mutations produced core peptide variants that had intermediate stages of PTM enzyme modifications, supporting the concept that PTM enzyme modifications, secondary cleavage, and transport are occurring in a highly coordinated fashion.ImportanceMutacin 1140 belongs to the class I lantibiotic family of ribosomally synthesized and posttranslationally modified peptides (RiPPs). The biosynthesis of mutacin 1140 is a highly efficient process which does not lead to a discernible level of production of partially modified core peptide variants. The products isolated from an extensive mutagenesis study on the leader and core peptides of mutacin 1140 show that the posttranslational modifications (PTMs) on the core peptide occur under a highly coordinated dynamic process. PTMs are dictated by the distance of the core peptide modifiable residues from PTM enzyme active sites. The formation of lanthionine rings aids in the formation of successive PTMs, as was observed in a peptide variant lacking a C-terminal decarboxylation.

Project description:Owing to extensive metagenomic studies, we now have access to numerous sequences of novel bacteriocin-like antimicrobial peptides encoded by various cultivable and noncultivable bacteria. However, relatively rarely, we even have access to these cultivable strains to examine the potency and the targets of the predicted bacteriocins. In this study, we evaluated a heterologous biosynthetic system to produce biologically active nonnative novel lantibiotics, which are modified bacteriocins. We chose Streptococcus mutans, a dental pathogen, as the host organism because it is genetically easy to manipulate and is inherently a prolific producer of various bacteriocins. We chose the S. mutans T8 strain as the host, which produces the lantibiotic mutacin II, to express 10 selected homologs of mutacin II identified from GenBank. These lantibiotic peptides either are novel or have been studied very minimally. The core regions of the selected lantibiotic peptides were fused to the leader sequence of the mutacin II peptide and integrated into the chromosome such that the core region of the native mutacin II was replaced with the new core sequences. By this approach, using the mutacin II biosynthesis machinery, we obtained one bioactive novel lantibiotic peptide with 52% different residues compared to the mutacin II core region. This unknown lantibiotic is encoded by Streptococcus agalactiae and Streptococcus ovuberis strains. Since this peptide displays some homology with nukacin ISK-1, we named it nukacin Spp. 2. This study demonstrated that the mutacin II biosynthesis machinery can be successfully used as an efficient system for the production of biologically active novel lantibiotics. IMPORTANCE In this study, we report for the first time that Streptococcus mutans can be used as a host to produce various nonnative lantibiotics. We showed that in the T8 strain, we could produce bioactive lacticin 481 and nukacin ISK-1, both of which are homologs of mutacin II, using T8's modification and secretion apparatus. Similarly, we also synthesized a novel bioactive lantibiotic, which we named nukacin Spp. 2.

Dataset Information

Diacylglycerol kinase is involved in regulation of expression of the lantibiotic mutacin II of Streptococcus mutans.

Publications

Diacylglycerol kinase is involved in regulation of expression of the lantibiotic mutacin II of Streptococcus mutans.

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