Sigma factors of RNA polymerase in the pathogenic spirochaete Leptospira interrogans, the causative agent of leptospirosis

The aim of this review is to summarize the current knowledge on the role of s factors in a highly invasive spirochaete Leptospira interrogans responsible for leptospirosis that affects many mammals, including humans. This disease has a significant impact on public health and the economy worldwide. In bacteria, s factors are the key regulators of gene expression at the transcriptional level and therefore play an important role in bacterial adaptative response to different environmental stimuli. These factors form a holoenzyme with the RNA polymerase core enzyme and then direct it to specific promoters, which results in turning on selected genes. Most bacteria possess several different s factors that enable them to maintain basal gene expression, as well as to regulate gene expression in response to specific environmental signals. Recent comparative genomics and in silico genome-wide analyses have revealed that the L. interrogans genome, consisting of two circular chromosomes, encodes a total of 14 s factors. Among them, there is one putative housekeeping s(70)-like factor, and three types of alternative s factors, i.e., one s(54), one s(28) and 11 putative ECF (extracytoplasmic function) s(E)-type factors. Here, characteristics of these putative s factors and their possible role in the L. interrogans gene regulation (especially in this pathogen's adaptive response to various environmental conditions, an important determinant of leptospiral virulence), are presented.

Automated summary

This review aims to summarize the current understanding of the role of s factors in Leptospira interrogans, a highly invasive spirochaete responsible for leptospirosis. The disease has a significant impact on public health and the global economy. S factors are key regulators of gene expression in bacteria and play a crucial role in bacterial adaptative response to different environmental stimuli. The L. interrogans genome encodes a total of 14 s factors, including one housekeeping factor and three types of alternative factors. The characteristics and possible role of these factors in gene regulation and pathogen adaptability are discussed.