Thursday, August 16, 2012: 8:30 AM
Meeting Room 5, Columbia Hall, Terrace level (Washington Hilton)
The ongoing characterization of base pairing small RNAs (sRNAs) in bacteria is revealing integral roles in gene regulatory networks (1). In some cases, the sRNAs act in parallel with transcription factors. For example, Spot 42 RNA plays a broad role in catabolite repression in Escherichia coli by repressing translation of genes involved in the consumption of diverse non-preferred carbon sources. Many of these same genes are transcriptionally activated by the global regulator CRP. Since CRP represses Spot 42, these regulators participate in a specific circuit called a multioutput feedforward loop. We found that this loop can reduce leaky expression of target genes in the presence of glucose and can maintain repression of target genes under changing nutrient conditions (2). In other cases, sRNAs control the expression of transcription factors. For example, McaS, represses synthesis of CsgD and activates synthesis of FlhD, key regulators of motility, adding to the growing list of key transcription factors whose synthesis is controlled by an array of small RNAs (3). We suggest that sRNAs can no longer be ignored in any regulatory network.
(1) Beisel C. L. and Storz G. (2010) FEMS Microbiol. Rev. 34, 866-882.
(2) Beisel C.L. and Storz G. (2011) Mol. Cell 41, 286-297.
(3) Thomason M.K., Fontaine F., De Lay N. and Storz G. (2012) Mol. Microbiol. 84, 17-35.