RNA Helicase Important for Listeria monocytogenes Hemolytic Activity and Virulence Factor Expression.
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.
Department of Molecular Biology, Molecular Infection Medicine, Sweden (MIMS), and Umeå Center for Microbial Research (UCMR), Umeå University, Umeå, Sweden.
Sakura
S
Netterling
Department of Molecular Biology, Molecular Infection Medicine, Sweden (MIMS), and Umeå Center for Microbial Research (UCMR), Umeå University, Umeå, Sweden.
Caroline
C
Bäreclev
Department of Molecular Biology, Molecular Infection Medicine, Sweden (MIMS), and Umeå Center for Microbial Research (UCMR), Umeå University, Umeå, Sweden.
Karolis
K
Vaitkevicius
Department of Molecular Biology, Molecular Infection Medicine, Sweden (MIMS), and Umeå Center for Microbial Research (UCMR), Umeå University, Umeå, Sweden jorgen.johansson@molbiol.umu.se.
Jörgen
J
Johansson
D000818:Animals; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D001427:Bacterial Toxins / Q000096:biosynthesis / Q000235:genetics; D018938:Caco-2 Cells; D002460:Cell Line; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics*; D006360:Heat-Shock Proteins / Q000096:biosynthesis / Q000235:genetics; D006460:Hemolysin Proteins / Q000096:biosynthesis / Q000235:genetics; D006461:Hemolysis / Q000235:genetics*; D006801:Humans; D008089:Listeria monocytogenes / Q000235:genetics / Q000472:pathogenicity*; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics; D051379:Mice; D010454:Peptide Termination Factors / Q000235:genetics / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000235:genetics; D020365:RNA Helicases / Q000235:genetics*; D037521:Virulence Factors / Q000096:biosynthesis / Q000235:genetics*
D001426:Bacterial Proteins; D001427:Bacterial Toxins; D006360:Heat-Shock Proteins; D006460:Hemolysin Proteins; D008565:Membrane Proteins; D010454:Peptide Termination Factors; C545356:PrfA protein, Listeria monocytogenes; D037521:Virulence Factors; C072980:actA protein, Listeria monocytogenes; D020365:RNA Helicases; C038705:hlyA protein, Listeria monocytogenes