title: Glutamine synthetase and glucose-6-phosphate isomerase are adhesive moonlighting proteins of Lactobacillus crispatus released by epithelial cathelicidin LL-37.
abstract: Glutamine synthetase (GS) and glucose-6-phosphate isomerase (GPI) were identified as novel adhesive moonlighting proteins of Lactobacillus crispatus ST1. Both proteins were bound onto the bacterial surface at acidic pHs, whereas a suspension of the cells to pH 8 caused their release into the buffer, a pattern previously observed with surface-bound enolase and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) of L. crispatus. The pH shift was associated with a rapid and transient increase in cell wall permeability, as measured by cell staining with propidium iodide. A gradual increase in the release of the four moonlighting proteins was also observed after the treatment of L. crispatus ST1 cells with increasing concentrations of the antimicrobial cationic peptide LL-37, which kills bacteria by disturbing membrane integrity and was here observed to increase the cell wall permeability of L. crispatus ST1. At pH 4, the fusion proteins His(6)-GS, His(6)-GPI, His(6)-enolase, and His(6)-GAPDH showed localized binding to cell division septa and poles of L. crispatus ST1 cells, whereas no binding to Lactobacillus rhamnosus GG was detected. Strain ST1 showed a pH-dependent adherence to the basement membrane preparation Matrigel. Purified His(6)-GS and His(6)-GPI proteins bound to type I collagen, and His(6)-GS also bound to laminin, and their level of binding was higher at pH 5.5 than at pH 6.5. His(6)-GS also expressed a plasminogen receptor function. The results show the strain-dependent surface association of moonlighting proteins in lactobacilli and that these proteins are released from the L. crispatus surface after cell trauma, under conditions of alkaline stress, or in the presence of the antimicrobial peptide LL-37 produced by human cells.
authors.affiliation: Division of General Microbiology, Department of Biosciences, University of Helsinki, Helsinki, Finland.
authors.forename: Veera
authors.initials: V
authors.lastname: Kainulainen
authors.forename: Vuokko
authors.initials: V
authors.lastname: Loimaranta
authors.forename: Anna
authors.initials: A
authors.lastname: Pekkala
authors.forename: Sanna
authors.initials: S
authors.lastname: Edelman
authors.forename: Jenni
authors.initials: J
authors.lastname: Antikainen
authors.forename: Riikka
authors.initials: R
authors.lastname: Kylväjä
authors.forename: Maiju
authors.initials: M
authors.lastname: Laaksonen
authors.forename: Liisa
authors.initials: L
authors.lastname: Laakkonen
authors.forename: Jukka
authors.initials: J
authors.lastname: Finne
authors.forename: Timo K
authors.initials: TK
authors.lastname: Korhonen
mesh_terms: D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology*; D001422:Bacterial Adhesion / Q000502:physiology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D005956:Glucose-6-Phosphate Isomerase / Q000235:genetics / Q000378:metabolism*; D005974:Glutamate-Ammonia Ligase / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007778:Lactobacillus / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D054804:Cathelicidins
chemical_list: D023181:Antimicrobial Cationic Peptides; D001426:Bacterial Proteins; D008565:Membrane Proteins; D005956:Glucose-6-Phosphate Isomerase; D005974:Glutamate-Ammonia Ligase; D054804:Cathelicidins