Molecular switches — the ON and OFF of bacterial phase variation

Authors

  • Ian R. Henderson,

    1. Center for Vaccine Development, Department of Pediatrics, University of Maryland School of Medicine, 685 West Baltimore Street, Baltimore, MD 21201, USA.,
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  • Peter Owen,

    1. Department of Microbiology, Moyne Institute for Preventive Medicine, Trinity College, Dublin 2, Ireland.
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  • James P. Nataro

    1. Center for Vaccine Development, Department of Pediatrics, University of Maryland School of Medicine, 685 West Baltimore Street, Baltimore, MD 21201, USA.,
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Ian R. Henderson. E-mail ihenders@umaryland.edu; Tel. (+1) 410 7067376; Fax (+1) 410 7066205.

Abstract

The expression of most bacterial genes is controlled at the level of transcription via promoter control mechanisms that permit a graded response. However, an increasing number of bacterial genes are found to exhibit an ‘all-or-none’ control mechanism that adapts the bacterium to more than one environment. One such mechanism is phase variation, traditionally defined as the high-frequency ON↔OFF switching of phenotype expression. Phase variation events are usually random, but may be modulated by environmental conditions. The mechanisms of phase variation events and their significance within the microbial community are discussed here.

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