Identification and characterization of genes encoding sex pheromone cAM373 activity in Enterococcus faecalis and Staphylococcus aureus

Authors

  • Susan E. Flannagan,

    1. Department of Biologic and Materials Sciences, School of Dentistry, The University of Michigan, 1011 N. University Ave., Ann Arbor, MI 48109-1078, USA.
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  • Don B. Clewell

    Corresponding author
    1. Department of Biologic and Materials Sciences, School of Dentistry, The University of Michigan, 1011 N. University Ave., Ann Arbor, MI 48109-1078, USA.
    2. Department of Microbiology and Immunology, School of Medicine, The University of Michigan, Ann Arbor, MI 48109, USA.
    • *For correspondence at the Department of Biologic and Materials Sciences. E-mail dclewell@umich.edu; Tel. (+1) 734 763 0117; Fax (+1) 734 763 9905.

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  • *For correspondence at the Department of Biologic and Materials Sciences. E-mail dclewell@umich.edu; Tel. (+1) 734 763 0117; Fax (+1) 734 763 9905.

Summary

The sex pheromone cAM373 of Enterococcus faecalis and the related staph-cAM373 of Staphylococcus aureus were found to correspond to heptapeptides located within the C-termini of the signal sequences of putative prelipoproteins. The deduced mature forms of the lipoproteins share no detectable homology and presumably serve unrelated functions in the cells. The chromosomally encoded genetic determinants for production of the pheromones have been identified and designated camE (encoding cAM373) and camS (encoding staph-cAM373). Truncated and full-length clones of camE were generated in Escherichia coli, in which cAM373 activity was expressed. In E. faecalis, insertional inactivation in the middle of camE had no detectable phenotypic effects on the pheromone system. Establishment of an in frame translation stop codon within the signal sequence resulted in reduction of cAM373 activity to 3% of normal levels. The camS determinant has homologues in Staphylococcus epidermidis, Bacillus subtilis and Listeria monocytogenes; however, corresponding heptapeptides present within those sequences do not resemble staph-cAM373 closely. The particular significance of staph-cAM373 as a potential intergeneric inducer of transfer-proficient genetic elements is discussed.

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