title: DExD-box RNA-helicases in Listeria monocytogenes are important for growth, ribosomal maturation, rRNA processing and virulence factor expression.
abstract: RNA-helicases are proteins required for the unwinding of occluding secondary RNA structures, especially at low temperatures. In this work, we have deleted all 4 DExD-box RNA helicases in various combinations in the Gram-positive pathogen Listeria monocytogenes. Our results show that 3 out of 4 RNA-helicases were important for growth at low temperatures, whereas the effect was less prominent at 37°C. Over-expression of one RNA-helicase, Lmo1450, was able to overcome the reduced growth of the quadruple mutant strain at temperatures above 26°C, but not at lower temperatures. The maturation of ribosomes was affected in different degrees in the various strains at 20°C, whereas the effect was marginal at 37°C. This was accompanied by an increased level of immature 23S rRNA precursors in some of the RNA-helicase mutants at low temperatures. Although the expression of the PrfA regulated virulence factors ActA and LLO decreased in the quadruple mutant strain, this strain showed a slightly increased infection ability. Interestingly, even though the level of the virulence factor LLO was decreased in the quadruple mutant strain as compared with the wild-type strain, the hly-transcript (encoding LLO) was increased. Hence, our results could suggest a role for the RNA-helicases during translation. In this work, we show that DExD-box RNA-helicases are involved in bacterial virulence gene-expression and infection of eukaryotic cells.
authors.affiliation: a Department of Molecular Biology ; Umeå University ; Umeå , Sweden.
authors.forename: Caroline
authors.initials: C
authors.lastname: Bäreclev
authors.forename: Karolis
authors.initials: K
authors.lastname: Vaitkevicius
authors.forename: Sakura
authors.initials: S
authors.lastname: Netterling
authors.forename: Jörgen
authors.initials: J
authors.lastname: Johansson
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D018938:Caco-2 Cells; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008089:Listeria monocytogenes / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D050296:Microbial Viability / Q000235:genetics; D009154:Mutation; D010454:Peptide Termination Factors / Q000235:genetics / Q000378:metabolism; D020365:RNA Helicases / Q000235:genetics* / Q000378:metabolism; D012335:RNA, Ribosomal / Q000235:genetics* / Q000378:metabolism; D012338:RNA, Ribosomal, 23S / Q000235:genetics / Q000378:metabolism; D012270:Ribosomes / Q000235:genetics* / Q000378:metabolism; D013696:Temperature; D014774:Virulence / Q000235:genetics; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D007527:Isoenzymes; D008565:Membrane Proteins; D010454:Peptide Termination Factors; C545356:PrfA protein, Listeria monocytogenes; D012335:RNA, Ribosomal; D012338:RNA, Ribosomal, 23S; D037521:Virulence Factors; C072980:actA protein, Listeria monocytogenes; D020365:RNA Helicases
keywords: DExD-box RNA-helicases; LLO; Listeria monocytogenes; bacterial infection; hly; translation