title: H-NS Nucleoid Protein Controls Virulence Features of Klebsiella pneumoniae by Regulating the Expression of Type 3 Pili and the Capsule Polysaccharide.
abstract: Klebsiella pneumoniae is an opportunistic pathogen causing nosocomial infections. Main virulence determinants of K. pneumoniae are pili, capsular polysaccharide, lipopolysaccharide, and siderophores. The histone-like nucleoid-structuring protein (H-NS) is a pleiotropic regulator found in several gram-negative pathogens. It has functions both as an architectural component of the nucleoid and as a global regulator of gene expression. We generated a Δhns mutant and evaluated the role of the H-NS nucleoid protein on the virulence features of K. pneumoniae. A Δhns mutant down-regulated the mrkA pilin gene and biofilm formation was affected. In contrast, capsule expression was derepressed in the absence of H-NS conferring a hypermucoviscous phenotype. Moreover, H-NS deficiency affected the K. pneumoniae adherence to epithelial cells such as A549 and HeLa cells. In infection experiments using RAW264.7 and THP-1 differentiated macrophages, the Δhns mutant was less phagocytized than the wild-type strain. This phenotype was likely due to the low adherence to these phagocytic cells. Taken together, our data indicate that H-NS nucleoid protein is a crucial regulator of both T3P and CPS of K. pneumoniae.
authors.affiliation: Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Hospital de PediatríaMexico City, Mexico; Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico NacionalMexico City, Mexico.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Ares
authors.affiliation: Unidad de Investigación en Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México Mexico City, Mexico.
authors.forename: José L
authors.initials: JL
authors.lastname: Fernández-Vázquez
authors.affiliation: Unidad de Investigación en Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México Mexico City, Mexico.
authors.forename: Roberto
authors.initials: R
authors.lastname: Rosales-Reyes
authors.affiliation: Unidad de Investigación en Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México Mexico City, Mexico.
authors.forename: Ma Dolores
authors.initials: MD
authors.lastname: Jarillo-Quijada
authors.affiliation: Cell Biology Institute, University of Bonn Bonn, Germany.
authors.forename: Kristine
authors.initials: K
authors.lastname: von Bargen
authors.affiliation: Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Hospital de Pediatría Mexico City, Mexico.
authors.forename: Javier
authors.initials: J
authors.lastname: Torres
authors.affiliation: Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional Mexico City, Mexico.
authors.forename: Jorge A
authors.initials: JA
authors.lastname: González-y-Merchand
authors.affiliation: Unidad de Investigación en Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México Mexico City, Mexico.
authors.forename: María D
authors.initials: MD
authors.lastname: Alcántar-Curiel
authors.affiliation: Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Hospital de Pediatría Mexico City, Mexico.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: De la Cruz
mesh_terms: D001422:Bacterial Adhesion / Q000235:genetics; D016667:Bacterial Capsules / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D010861:Fimbriae, Bacterial / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006367:HeLa Cells; D006801:Humans; D007710:Klebsiella Infections / Q000276:immunology / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity*; D008264:Macrophages / Q000276:immunology; D010587:Phagocytosis / Q000276:immunology; D011135:Polysaccharides, Bacterial / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C031908:H-NS protein, bacteria; D011135:Polysaccharides, Bacterial
keywords: H-NS; K. pneumoniae; T3P; adherence; capsule; phagocytosis; virulence