Cross Talk between SigB and PrfA in Listeria monocytogenes Facilitates Transitions between Extra- and Intracellular Environments

Abstract

SUMMARY The foodborne pathogen Listeria monocytogenes can modulate its transcriptome and proteome to ensure its survival during transmission through vastly differing environmental conditions. While L. monocytogenes utilizes a large array of regulators to achieve survival and growth in different intra- and extrahost environments, the alternative sigma factor σB and the transcriptional activator of virulence genes protein PrfA are two key transcriptional regulators essential for responding to environmental stress conditions and for host infection. Importantly, emerging evidence suggests that the shift from extrahost environments to the host gastrointestinal tract and, subsequently, to intracellular environments requires regulatory interplay between σB and PrfA at transcriptional, posttranscriptional, and protein activity levels. Here, we review the current evidence for cross talk and interplay between σB and PrfA and their respective regulons and highlight the plasticity of σB and PrfA cross talk and the role of this cross talk in facilitating successful transition of L. monocytogenes from diverse extrahost to diverse extra- and intracellular host environments.

Transcriptome Sequencing of Listeria monocytogenes Reveals Major Gene Expression Changes in Response to Lactic Acid Stress Exposure but a Less Pronounced Response to Oxidative Stress

“…The general stress response of L. monocytogenes is connected to the organism's pathogenic lifestyle by direct interactions with virulence factors. Notably, σ B directly regulates the transcription of two internalins involved in initial host cell invasion, inlA and inlB (Chaturongakul et al, 2008), and a complex regulatory interaction between the σ B and PrfA regulons is necessary for virulence (Chaturongakul et al, 2008;Gaballa et al, 2019). In this study, inlA (which possesses a premature stop codon in 6179 and is therefore annotated as two separate genes) was upregulated by log2fold changes of 7.07 and 6.95 in 6179 and 8.43 in R479a.…”

Transcriptome analysis of differential gene expression in the longissimus dorsi muscle from Debao and landrace pigs based on RNA-sequencing

“…Pigs are indispensable for human life, especially in China, where the population clearly depends on pork and pig is the main agricultural economic animal [21][22][23][24]. However, with the rapid development of China's economy, people's living standards have greatly improved, the requirements for pork are becoming increasingly higher, and the demand for meat taste could not be satisfied with the current commercial pork [25]. The improvement in the taste of pork was mainly related to the fat content in the muscles of pigs [26].…”

The σB-Mediated General Stress Response of Listeria monocytogenes: Life and Death Decision Making in a Pathogen

“…To establish an infection L. monocytogenes needs to survive under the harsh conditions of the gastrointestinal (GI) tract, including the acidic conditions of the stomach, osmotic stress in the small intestine, and the presence of bile salts in the duodenum ( Sleator et al, 2009 ; Gaballa et al, 2019 ; Tiensuu et al, 2019 ). Survival in the presence of these stresses is partially dependent on σ B , as an intragastrically inoculated Δ sigB strain exhibits attenuated virulence ( Garner et al, 2006 ; Oliver et al, 2010 ).…”

“…A growing body of evidence points toward a complex two-way regulatory network between σ B and the master regulator of virulence, PrfA ( Gaballa et al, 2019 ; Tiensuu et al, 2019 ). σ B is also responsible for the regulation of the RNA chaperone Hfq which also plays a role in virulence and osmotic stress resistance ( Christiansen et al, 2004 ).…”

“…Finally the role of the GSR in modulating the virulence of L. monocytogenes is still an open question. There are multiple lines of evidence suggesting regulatory crosstalk between σ B and PrfA and these need to be explored further ( Gaballa et al, 2019 ; Tiensuu et al, 2019 ). While σ B plays an essential role during the GI stage of the infectious cycle, it is less important during the systemic stages, where PrfA appears to be the dominant regulator.…”