The RNA polymerase gene specificity factor σ54 is required for homogeneous non-planktonic growth of uropathogenic Escherichia coli

Abstract

AbstractThe canonical function of a bacterial sigma (σ) factor is to determine the gene specificity of the RNA polymerase (RNAP). In several diverse bacterial species, the σ54 factor uniquely confers distinct functional and regulatory properties on the RNAP. A hallmark feature of the σ54-RNAP is the obligatory requirement for an activator ATPase to allow transcription initiation. The genes that rely upon σ54 for their transcription have a wide range of different functions suggesting that the repertoire of functions performed by genes, directly or indirectly affected by σ54, is not yet exhaustive. By comparing the non-planktonic growth properties of prototypical enteropathogenic, uropathogenic and non-pathogenic Escherichia coli strains devoid of σ54, we uncovered σ54 as a determinant of homogenous non-planktonic growth specifically in the uropathogenic strain. Notably, bacteria devoid of individual activator ATPases of the σ54-RNAP do not phenocopy the σ54 mutant strain. It seems that σ54’s role as a determinant of homogenous non-planktonic growth represents a putative non-canonical function of σ54 in regulating genetic information flow.