MOLECULAR BIOLOGY: Making a Switch

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Science  23 Jul 2004:
Vol. 305, Issue 5683, pp. 453b
DOI: 10.1126/science.305.5683.453b

In the past couple of years, numerous small noncoding RNA molecules have been shown to participate as regulators of gene expression in plants and animals. Lenz et al. show how they are used within a bacterial quorum sensing pathway to achieve an all-or-none type of control. Bacteria have a need to know how densely they populate the local environment, because investing in some behaviors only makes sense if everyone takes part, and the quorum-sensing circuits—containing the customary complement of ligands, receptors, kinases, and transcriptional regulators—send and decode these signals. The authors identified five distinct small RNAs in the bioluminescent marine organism Vibrio harveyi (and four in the human pathogen V. cholerae) and found that any one of the five suffices for signaling, meaning that transcription of luciferase is repressed at low population densities. However, having multiple redundant small RNAs has the effect of making the transition from individualistic to communal behavior an abrupt on/off switch. — GJC

Cell 118, 69 (2004).

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