Collection of sigma factors in Escherichia coli

Sigma factors play important roles as transcription factors in bacterial species. Able to regulate the transcription of many genes in its regulon, transcription of particular sigma factors signals the activation of an entire set of genes for initiating a change in cell differentiation or entry into survival response such as responding to heat shock. Collated here is a partial list of sigma factors in <i>Escherichia coli</i> that may find use in understanding the bacterial cell biology literature or serving as an initial guide into the multi-facet world of bacterial gene expression regulation.