[Frontiers in Bioscience 7, d1798-1814, August 1, 2002]


Jean-Pierre Claverys 1 and Leiv Sigve Havarstein 21

Laboratoire de Microbiologie et Génétique Moléculaire, UMR 5100 CNRS-Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex, France. 2 Department of Chemistry and Biotechnology, Agricultural University of Norway, PO Box 5040, N-1432, As, Norway

1. Abstract
2. Introduction
3. Regulation of competence development in S. pneumoniae
3.1. Identification of the competence stimulating peptide (CSP)
3.2. Processing and secretion of CSP
3.2.1. A family of proteolytic ABC-transporters
3.2.2. The double-glycine leader
3.3. The competence cascade
3.3.1. The ComCDE signal transduction pathway ComD, the CSP receptor The ComE response regulator An autocatalytic regulatory loop The com genes can be distributed into two classes, early and late
3.3.2. The ComX regulon
3.3.3. The shutoff of competence
3.4. Control of basal level expression of comAB and comCDE
3.4.1. The oligopeptide permease
3.4.2. cup mutants underline the importance of comCDE autoregulation
3.4.3. Limited CSP export capacity also controls comCDE autoinduction
3.4.4. The CiaRH TCS and competence
3.4.5. Oxygen and competence
3.4.6. Additional regulatory signals TCS02 The ClpP stress response protein Purine metabolism: purine pools as internal stress signals? Membrane lipid composition and peptidoglycan synthesis
3.5. competence, a general stess response of S. pneumoniae?
4.Regulation of competence development in other streptococci
5. A closely related gene regulation system in S. pneumoniae
6. CSP for counting cells or cell-cell signaling?
6.1. Counting cells for genetic transfer or other purposes?
6.1.1. Counting donor cells for intraspecies exchanges
6.1.2. Counting recipient cells for horizontal transfer
6.1.3. Counting cells for competence-dependent virulence
6.1.4. Counting cells for competence-dependent formation of biofilms
6.2. Cell-cell signaling: the alarmone hypothesis
7. Perspectives
8. Acknowledgement
9. References


Bacteria, which often are subjected to fluctuations in nutrients, temperature, radiation, pH, etc…, adapt to the physico-chemical environment they live in by making the appropriate changes in their gene expression patterns. During the last decades it has become increasingly clear that bacteria, in addition, have a "social life", and that changes in gene expression can also be elicited by the presence of other bacteria. Traditionally bacteria have been viewed as solitary organisms that in general do not interact with other bacteria in a coordinated manner. Recent advances in the field of bacterial cell-to-cell communication has proved this to be a misconception, and mounting evidence now show that bacterial group behaviour is ubiquitous in nature.