title: NlpI contributes to Escherichia coli K1 strain RS218 interaction with human brain microvascular endothelial cells.
abstract: Escherichia coli K1 is the most common Gram-negative bacillary organism causing neonatal meningitis. E. coli K1 binding to and invasion of human brain microvascular endothelial cells (HBMECs) is a prerequisite for its traversal of the blood-brain barrier (BBB) and penetration into the brain. In the present study, we identified NlpI as a novel bacterial determinant contributing to E. coli K1 interaction with HBMECs. The deletion of nlpI did not affect the expression of the known bacterial determinants involved in E. coli K1-HBMEC interaction, such as type 1 fimbriae, flagella, and OmpA, and the contribution of NlpI to HBMECs binding and invasion was independent of those bacterial determinants. Previous reports have shown that the nlpI mutant of E. coli K-12 exhibits growth defect at 42 degrees C at low osmolarity, and its thermosensitive phenotype can be suppressed by a mutation on the spr gene. The nlpI mutant of strain RS218 exhibited similar thermosensitive phenotype, but additional spr mutation did not restore the ability of the nlpI mutant to interact with HBMECs. These findings suggest the decreased ability of the nlpI mutant to interact with HBMECs is not associated with the thermosensitive phenotype. NlpI was determined as an outer membrane-anchored protein in E. coli, and the nlpI mutant was defective in cytosolic phospholipase A(2)alpha (cPLA(2)alpha) phosphorylation compared to the parent strain. These findings illustrate the first demonstration of NlpI's contribution to E. coli K1 binding to and invasion of HBMECs, and its contribution is likely to involve cPLA(2)alpha.
authors.affiliation: Institute of Molecular Medicine, National Cheng Kung University Medical College, Tainan, Taiwan.
authors.forename: Ching-Hao
authors.initials: CH
authors.lastname: Teng
authors.forename: Yu-Ting
authors.initials: YT
authors.lastname: Tseng
authors.forename: Ravi
authors.initials: R
authors.lastname: Maruvada
authors.forename: Donna
authors.initials: D
authors.lastname: Pearce
authors.forename: Yi
authors.initials: Y
authors.lastname: Xie
authors.forename: Maneesh
authors.initials: M
authors.lastname: Paul-Satyaseela
authors.forename: Kwang Sik
authors.initials: KS
authors.lastname: Kim
mesh_terms: D001422:Bacterial Adhesion / Q000502:physiology*; D001425:Bacterial Outer Membrane Proteins / Q000502:physiology; D015153:Blotting, Western; D001921:Brain / Q000098:blood supply / Q000382:microbiology*; D042783:Endothelial Cells / Q000382:microbiology*; D004926:Escherichia coli / Q000235:genetics / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000502:physiology*; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000502:physiology; D005407:Flagella / Q000235:genetics / Q000502:physiology; D054513:Group IV Phospholipases A2 / Q000502:physiology; D006801:Humans; D007231:Infant, Newborn; D008074:Lipoproteins / Q000235:genetics / Q000502:physiology*; D020814:Meningitis, Escherichia coli / Q000382:microbiology*; D008833:Microcirculation
chemical_list: D001425:Bacterial Outer Membrane Proteins; D029968:Escherichia coli Proteins; D008074:Lipoproteins; C120330:NlpI protein, E coli; C078167:OMPA outer membrane proteins; D054513:Group IV Phospholipases A2