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MIC 231 , a naturally occurring mobile insertion cassette from Bacillus cereus
Author(s) -
Chen Yahua,
Braathen Pia,
Léonard Catherine,
Mahillon Jacques
Publication year - 1999
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.1999.01388.x
Subject(s) - biology , mobile genetic elements , bacillus cereus , cereus , escherichia coli , transposable element , genetics , gene , plasmid , horizontal gene transfer , microbiology and biotechnology , mutant , phylogenetics , bacteria
Recent dissection of numerous plasmids and transposable elements has given more credence to the modular organization of these genetic and genomic entities. Although many variations on each theme exist, the number of basic functional cassettes is thought to be relatively limited. In this paper, a novel type of mobile cassette is described. A naturally occurring assemblage consisting of two left IS 231 ends flanking a d ‐stereospecific endopeptidase ( adp ) gene was found in several natural isolates of Bacillus cereus . This 1.9 kb genetic entity was shown to transpose in the presence of IS 231A transposase, not only in Escherichia coli but also in Bacillus . The acronym MIC 231 is proposed for this mobile insertion cassette trans ‐activated (teletransposed) by IS 231 . Using ( d ‐Phe) 4 tetrapeptide as substrate, the endopeptidase activity of the MIC 231 adp gene could be demonstrated in E. coli and B. subtilis . Interestingly, this d ‐stereospecific endopeptidase activity was not limited to the original B. cereus isolates but was also detected in all but one of the 69 B. cereus sensu lato strains tested, indicating its important, yet dispensable, biological function. However, inactivation of the MIC 231 adp gene in two B. cereus strains did not result in any detectable variation of their activity on ( d ‐Phe) 4 , suggesting the presence of other distantly related adp gene(s). Thus, although the exact role of MIC 231 adp remains elusive, its presence inside a mobile cassette represents the archetype of a novel insertion sequence modular organization.