RNA Helicase Important for Listeria monocytogenes Hemolytic Activity and Virulence Factor Expression

Abstract

RNA helicases have been shown to be important for the function of RNA molecules at several levels, although their putative involvement in microbial pathogenesis has remained elusive. We have previously shown that Listeria monocytogenes DExD-box RNA helicases are important for bacterial growth, motility, ribosomal maturation, and rRNA processing. We assessed the importance of the RNA helicase Lmo0866 (here named CshA) for expression of virulence traits. We observed a reduction in hemolytic activity in a strain lacking CshA compared to the wild type. This phenomenon was less evident in strains lacking other RNA helicases. The reduced hemolysis was accompanied by lower expression of major listerial virulence factors in the ΔcshA strain, mainly listeriolysin O, but also to some degree the actin polymerizing factor ActA. Reduced expression of these virulence factors in the strain lacking CshA did not, however, correlate with a decreased level of the virulence regulator PrfA. When combining the ΔcshA knockout with a mutation creating a constitutively active PrfA protein (PrfA*), the effect of the ΔcshA knockout on LLO expression was negated. These data suggest a role for the RNA helicase CshA in posttranslational activation of PrfA. Surprisingly, although the expression of several virulence factors was reduced, the ΔcshA strain did not demonstrate any reduced ability to infect nonphagocytic cells compared to the wild-type strain.

RNA Helicase Mediates Competitive Fitness of Listeria monocytogenes on the Surface of Cantaloupe

“…Lastly, L1E4 was less hemolytic on blood agar plates than the parent strain or mutant M1A5, as also reported by others for helicase mutants of L. monocytogenes [13]. The pleiotropic phenotype of L1E4 is in agreement with the requirement for functional RNA helicases in diverse phenotypes of L. monocytogenes [11][12][13][14][15]. Four DEAD-box RNA helicase genes (lmo0866, lmo1246, lmo1450, lmo1722) have been identified in L. monocytogenes EGD-e [14][15][16].…”

“…The helicase mutant L1E4 was cold-sensitive, completely unable to grow in liquid or on agar media at 4 or 10 • C, as previously shown for other helicase mutants [11,12], in contrast to M1A5, which grew at these low temperatures similarly to strain 2858. Lastly, L1E4 was less hemolytic on blood agar plates than the parent strain or mutant M1A5, as also reported by others for helicase mutants of L. monocytogenes [13]. The pleiotropic phenotype of L1E4 is in agreement with the requirement for functional RNA helicases in diverse phenotypes of L. monocytogenes [11][12][13][14][15].…”

“…Originally isolated on the basis of its impaired motility, L1E4 was in addition cold-sensitive, had reduced colony size on agar media, and it was less hemolytic on blood agar plates than its parental strain. Since mutant M1A5 was not impaired in competitive fitness on Similarly to other helicase mutants of L. monocytogenes [11][12][13][14][15], L1E4 was impaired in multiple phenotypes. Originally isolated on the basis of its impaired motility, L1E4 was in addition cold-sensitive, had reduced colony size on agar media, and it was less hemolytic on blood agar plates than its parental strain.…”

Antibacterial and antivirulence effect of 6-N-hydroxylaminopurine inListeria monocytogenes

“…(26). Overnight cultures in LB were washed three times in minimal-media, diluted and incubated at 37°C with shaking.…”

Shotgun Label-Free Proteomic Analyses of the Oyster Parasite Perkinsusmarinus

“…Additional proteins that are important for the pathogenesis of P. marinus and a variety of bacterial and parasitic organisms were detected in at least two replicates, including: aldose reductase [20], betaine aldehyde dehydrogenase [21], helicases [15,22], malate dehydrogenase [6], and aspartyl aminopeptidase [23].…”