Abstract
Legionella pneumophila RpoS (LpRpoS), an alternative sigma factor of RNA polymerase (RNAP), is essential for virulence and stress resistance. To investigate the mechanism of RpoS in the intracellular pathogen L. pneumophila, we determined the high-resolution crystal structure of the LpRpoS 95–195 containing a partial region 1.2 and region 2. The structure of LpRpoS 95–195 reveals that the conserved residues are critical for promoter melting, DNA and core RNAP binding. The differences in regulatory factor binding site between Escherichia coli RpoS and LpRpoS suggest that LpRpoS may employ a distinct mechanism to recruit alternative regulatory factors controlling transcription initiation.
Highlights
Bacteria are able to rapidly sense and adapt to varying environmental conditions in order to survive
Coupled with mass spectrometry analysis, we determined that the crystallized fragment contains a partial region 1.2 and a region 2 of Legionella pneumophila RpoS (LpRpoS) 95–195 (Figure 1a)
RpoS play a role in stress response gene expression and production of virulence factors in
Summary
Bacteria are able to rapidly sense and adapt to varying environmental conditions in order to survive. Many bacteria require alternative sigma factors to initiate transcription and regulate the expression of a specific set of genes in order to adapt to changing environments. Legionella pneumophila, the causative agent of Legionnaires’ disease, is a Gram-negative facultative intracellular pathogen capable of multiplying in a wide spectrum of eukaryotic cells. It adopts a biphasic life cycle consisting of a replicative and transmissive phase in a host cell. To establish a replicative niche inside host cells and escape from host cell vacuoles, L. pneumophila has been shown to utilize RpoS to initiate the expression distinct groups of virulence factors for infection of host cells and intracellular growth [3]
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