title: Inhibition of Phagocytic Killing of Escherichia coli in Drosophila Hemocytes by RNA Chaperone Hfq.
abstract: An RNA chaperone of Escherichia coli, called host factor required for phage Qβ RNA replication (Hfq), forms a complex with small noncoding RNAs to facilitate their binding to target mRNA for the alteration of translation efficiency and stability. Although the role of Hfq in the virulence and drug resistance of bacteria has been suggested, how this RNA chaperone controls the infectious state remains unknown. In the present study, we addressed this issue using Drosophila melanogaster as a host for bacterial infection. In an assay for abdominal infection using adult flies, an E. coli strain with mutation in hfq was eliminated earlier, whereas flies survived longer compared with infection with a parental strain. The same was true with flies deficient in humoral responses, but the mutant phenotypes were not observed when a fly line with impaired hemocyte phagocytosis was infected. The results from an assay for phagocytosis in vitro revealed that Hfq inhibits the killing of E. coli by Drosophila phagocytes after engulfment. Furthermore, Hfq seemed to exert this action partly through enhancing the expression of σ(38), a stress-responsive σ factor that was previously shown to be involved in the inhibition of phagocytic killing of E. coli, by a posttranscriptional mechanism. Our study indicates that the RNA chaperone Hfq contributes to the persistent infection of E. coli by maintaining the expression of bacterial genes, including one coding for σ(38), that help bacteria evade host immunity.
authors.affiliation: Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan; School of Pharmacy, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan; and ashira@staff.kanazawa-u.ac.jp nakanaka@p.kanazawa-u.ac.jp.
authors.forename: Akiko
authors.identifier: 0000-0002-7811-4409
authors.initials: A
authors.lastname: Shiratsuchi
authors.affiliation: School of Pharmacy, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan; and.
authors.forename: Mao
authors.initials: M
authors.lastname: Nitta
authors.affiliation: School of Pharmacy, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan; and.
authors.forename: Ayumi
authors.initials: A
authors.lastname: Kuroda
authors.affiliation: Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan;
authors.forename: Chiharu
authors.initials: C
authors.lastname: Komiyama
authors.affiliation: School of Pharmacy, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan; and.
authors.forename: Mitsuko
authors.initials: M
authors.lastname: Gawasawa
authors.affiliation: Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan;
authors.forename: Naoto
authors.initials: N
authors.lastname: Shimamoto
authors.affiliation: Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan;
authors.forename: Tran Quoc
authors.initials: TQ
authors.lastname: Tuan
authors.affiliation: Faculty of Pharmaceutical Sciences, Suzuka University of Medical Sciences, Suzuka, Mie 513-0816, Japan.
authors.forename: Teppei
authors.initials: T
authors.lastname: Morita
authors.affiliation: Faculty of Pharmaceutical Sciences, Suzuka University of Medical Sciences, Suzuka, Mie 513-0816, Japan.
authors.forename: Hiroji
authors.initials: H
authors.lastname: Aiba
authors.affiliation: Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan; School of Pharmacy, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan; and ashira@staff.kanazawa-u.ac.jp nakanaka@p.kanazawa-u.ac.jp.
authors.forename: Yoshinobu
authors.identifier: 0000-0002-8767-3587
authors.initials: Y
authors.lastname: Nakanishi
mesh_terms: D000818:Animals; D015153:Blotting, Western; D004195:Disease Models, Animal; D004330:Drosophila / Q000382:microbiology*; D004926:Escherichia coli / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D006434:Hemocytes / Q000382:microbiology; D035001:Host Factor 1 Protein / Q000378:metabolism*; D010587:Phagocytosis / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014774:Virulence / Q000502:physiology
chemical_list: D029968:Escherichia coli Proteins; C087373:Hfq protein, E coli; D035001:Host Factor 1 Protein