Poster Sessions

MB -8

Errett Hobbs

E. C. Hobbs, J. A. Astarita, G. Storz

Small proteins and small RNAs involved in resistance to outer membrane stress in Escherichia coli: analysis of a sequence signature-tagged mutant collection

An abundance of genes coding for small proteins and small RNAs exists within the E. coli chromosome. Although many are highly conserved, the functions of the majority of these genes are unknown. The few characterized to date serve diverse roles; for instance, some act as intra- and intercellular signals, antibiotics, and regulators of outer membrane biogenesis. Elucidating the functions of the remaining small proteins and small RNAs would be greatly facilitated by the discovery of deletion phenotypes for individual genes. Toward this end, we generated 127 sequence signature-tagged mutants of genes coding for small proteins and small RNAs. We employed this collection in large-scale competition assays to identify eight deletion mutants that are sensitive and two deletion mutants that are resistant to outer membrane stress. Remarkably, deletion mutants of two extensively studied genes, ssrA and micA, were among the three strains most sensitive to outer membrane stress. In contrast, seven phenotypes were ascribed to deletions of genes of unknown function. We anticipate that this tagged mutant collection will serve as a springboard for future studies testing other stress conditions. The phenotypes so discovered will enable the study of small proteins and small RNAs by standard biochemical, genetic, and cytological methods.