title: Novel LanT associated lantibiotic clusters identified by genome database mining.
abstract: BACKGROUND
  Frequent use of antibiotics has led to the emergence of antibiotic resistance in bacteria. Lantibiotic compounds are ribosomally synthesized antimicrobial peptides against which bacteria are not able to produce resistance, hence making them a good alternative to antibiotics. Nisin is the oldest and the most widely used lantibiotic, in food preservation, without having developed any significant resistance against it. Having their antimicrobial potential and a limited number, there is a need to identify novel lantibiotics.
  
  
  RESULTS
  Identification of novel lantibiotic biosynthetic clusters from an ever increasing database of bacterial genomes, can provide a major lead in this direction. In order to achieve this, a strategy was adopted to identify novel lantibiotic biosynthetic clusters by screening the sequenced genomes for LanT homolog, which is a conserved lantibiotic transporter specific to type IB clusters. This strategy resulted in identification of 54 bacterial strains containing the LanT homologs, which are not the known lantibiotic producers. Of these, 24 strains were subjected to a detailed bioinformatic analysis to identify genes encoding for precursor peptides, modification enzyme, immunity and quorum sensing proteins. Eight clusters having two LanM determinants, similar to haloduracin and lichenicidin were identified, along with 13 clusters having a single LanM determinant as in mersacidin biosynthetic cluster. Besides these, orphan LanT homologs were also identified which might be associated with novel bacteriocins, encoded somewhere else in the genome. Three identified gene clusters had a C39 domain containing LanT transporter, associated with the LanBC proteins and double glycine type precursor peptides, the only known example of such a cluster is that of salivaricin.
  
  
  CONCLUSIONS
  This study led to the identification of 8 novel putative two-component lantibiotic clusters along with 13 having a single LanM and 3 with LanBC genes. Putative lantibiotic clusters identified here hold the potential for the discovery of novel lantibiotic(s).
authors.affiliation: Department of Biochemistry, Panjab University, Chandigarh, India.
authors.forename: Mangal
authors.initials: M
authors.lastname: Singh
authors.affiliation: Department of Biochemistry, Panjab University, Chandigarh, India.
authors.forename: Dipti
authors.initials: D
authors.lastname: Sareen
mesh_terms: D039903:Actinobacteria / Q000166:cytology / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D000409:Alanine / Q000031:analogs & derivatives*; D000900:Anti-Bacterial Agents / Q000096:biosynthesis* / Q000737:chemistry; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001692:Biological Transport; D057225:Data Mining; D030541:Databases, Genetic; D005798:Genes, Bacterial / Q000235:genetics*; D023281:Genomics; D005810:Multigene Family; D053038:Quorum Sensing; D013440:Sulfides
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D013440:Sulfides; C001520:lanthionine; D000409:Alanine