Overcoming the restriction barrier to plasmid transformation and targeted mutagenesis in Bifidobacterium breve UCC2003.

ABSTRACT: In silico analysis of the Bifidobacterium breve UCC2003 genome predicted two distinct loci, which encode three different restriction/modification systems, each comprising a modification methylase and a restriction endonuclease. Based on sequence homology and observed protection against restriction we conclude that the first restriction endonuclease, designated BbrI, is an isoschizomer of BbeI, the second, BbrII, is a neoschizomer of SalI, while the third, BbrIII, is an isoschizomer of PstI. Expression of each of the B. breve UCC2003 methylase-encoding genes in B. breve JCM 7017 established that BbrII and BbrIII are active and restrict incoming DNA. By exploiting knowledge on restriction/modification in B. breve UCC2003 we successfully increased the transformation efficiency to a level that allows the reliable generation of mutants by homologous recombination using a non-replicative plasmid.

SUBMITTER: O'Connell Motherway M 

PROVIDER: S-EPMC3815753 | biostudies-literature | 2009 May

REPOSITORIES: biostudies-literature