title: Complement protective epitopes and CD55-microtubule complexes facilitate the invasion and intracellular persistence of uropathogenic Escherichia coli.
abstract: BACKGROUND
  Escherichia coli-bearing Dr-adhesins (Dr+ E. coli) cause chronic pyelonephritis in pregnant women and animal models. This chronic renal infection correlates with the capacity of bacteria to invade epithelial cells expressing CD55. The mechanism of infection remains unknown.
  
  
  METHODS
  CD55 amino acids in the vicinity of binding pocket-Ser155 for Dr-adhesin were mutated to alanine and subjected to temporal gentamicin-invasion/gentamicin-survival assay in Chinese hamster ovary cells. CD55/microtubule (MT) responses were studied using confocal/electron microscopy, and 3-dimensional structure analysis.
  
  
  RESULTS
  Mutant analysis revealed that complement-protective CD55-Ser165 and CD55-Phe154 epitopes control E. coli invasion by coregulating CD55-MT complex expression. Single-point CD55 mutations changed E. coli to either a minimally invasive (Ser165Ala) or a hypervirulent pathogen (Phe154Ala). Thus, single amino acid modifications with no impact on CD55 structure and bacterial attachment can have a profound impact on E. coli virulence. While CD55-Ser165Ala decreased E. coli invasion and led to dormant intracellular persistence, intracellular E. coli in CD55-Phe154Ala developed elongated forms (multiplying within vacuoles), upregulated CD55-MT complexes, acquired CD55 coat, and escaped phagolysosomal fusion.
  
  
  CONCLUSIONS
  E. coli target complement-protective CD55 epitopes for invasion and exploit CD55-MT complexes to escape phagolysosomal fusion, leading to a nondestructive parasitism that allows bacteria to persist intracellularly.
authors.affiliation: Department of Microbiology and Immunology.
authors.forename: Tanu
authors.initials: T
authors.lastname: Rana
authors.forename: Rafia J
authors.initials: RJ
authors.lastname: Hasan
authors.forename: Stella
authors.initials: S
authors.lastname: Nowicki
authors.forename: Mathura S
authors.initials: MS
authors.lastname: Venkatarajan
authors.forename: Rajbir
authors.initials: R
authors.lastname: Singh
authors.forename: Petri T
authors.initials: PT
authors.lastname: Urvil
authors.forename: Vsevolod
authors.initials: V
authors.lastname: Popov
authors.forename: Werner A
authors.initials: WA
authors.lastname: Braun
authors.forename: Waldemar
authors.initials: W
authors.lastname: Popik
authors.forename: J Shawn
authors.initials: JS
authors.lastname: Goodwin
authors.forename: Bogdan J
authors.initials: BJ
authors.lastname: Nowicki
mesh_terms: D018830:Adhesins, Escherichia coli / Q000276:immunology / Q000378:metabolism; D000818:Animals; D018958:CD55 Antigens / Q000235:genetics / Q000378:metabolism*; D016466:CHO Cells; D003165:Complement System Proteins / Q000276:immunology*; D003412:Cricetulus; D004705:Endocytosis; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D008870:Microtubules / Q000378:metabolism*; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D011487:Protein Conformation; D056689:Uropathogenic Escherichia coli / Q000276:immunology* / Q000502:physiology*
chemical_list: D018830:Adhesins, Escherichia coli; D018958:CD55 Antigens; C465564:Dr adhesin, E coli; D050505:Mutant Proteins; D003165:Complement System Proteins
keywords: CD55; Dr+ E. coli; intracellular persistence; invasion; microtubules