Conservation of key elements of natural competence in Lactococcus lactis ssp

• Published in: FEMS microbiology letters Vol. 257; no. 1; pp. 32 - 42
• Main Authors: Wydau, Sandra, Dervyn, Rozenn, Anba, Jamila, Dusko Ehrlich, S., Maguin, Emmanuelle
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-04-2006; Oxford University Press; Wiley-Blackwell
• Subjects: Amino Acid Sequence; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Base Sequence; comX; Conservation; Conserved Sequence; Deoxyribonucleic acid; DNA; dprA; Gene expression; Gene Expression Regulation, Bacterial; Gene regulation; Gene transfer; Genes; genetic diversity; Genetic Variation; Genomes; Homology; Lactococcus lactis; Lactococcus lactis - classification; Lactococcus lactis - genetics; Lactococcus lactis - metabolism; late competence genes; Life Sciences; Membrane Proteins - chemistry; Membrane Proteins - genetics; Membrane Proteins - metabolism; Microbiology; Microbiology and Parasitology; Molecular Sequence Data; Nucleotide sequence; regulation; Sequence Analysis, DNA; Sigma factor; Sigma Factor - chemistry; Sigma Factor - genetics; Sigma Factor - metabolism; Species diversity; Strains (organisms); Transcription Factors - chemistry; Transcription Factors - genetics; Transcription Factors - metabolism; X; genetic diversity; A; regulation; sigma factor; late competence genes; GENETIC DIVERSITY; LATE COMPETENCE GENES; REGULATION; SIGMA FACTOR; dprA; comX; LACTOCOCCUS LACTIS
• ISSN: 0378-1097; 1574-6968
• DOI: 10.1111/j.1574-6968.2006.00141.x

Abstract
Natural competence is active in very diverse species of the bacterial kingdom and probably participates in horizontal gene transfer. Recently, the genome sequence of various species, including Lactococcus lactis, revealed the presence of homologues of competence genes in bacteria, which were not previously identified as naturally transformable. We investigated the conservation among lactococcal strains of key components of the natural competence process in streptococci: (i) comX which encodes a sigma factor, allowing the expression of the late competence genes involved in DNA uptake, (ii) its recognition site, the cin-box and (iii) dprA which encodes a protein shown to determine the fate of incoming DNA. The comX and dprA genes and the cin-box appeared conserved among strains, although some L. lactis ssp. lactis strains presented an inactivated dprA gene. We established that ComX controls the expression of the late competence genes in L. lactis. In conclusion, our work strongly suggests that ComX has the same role in streptococci and L. lactis, i.e. the regulation of late competence genes. It also allowed the identification of a set of L. lactis strains and the construction of a comX overexpression system, which should facilitate the investigation of the natural competence activity in lactococci.