title: Pseudomonas aeruginosa serA Gene Is Required for Bacterial Translocation through Caco-2 Cell Monolayers.
abstract: To specify critical factors responsible for Pseudomonas aeruginosa penetration through the Caco-2 cell epithelial barrier, we analyzed transposon insertion mutants that demonstrated a dramatic reduction in penetration activity relative to P. aeruginosa PAO1 strain. From these strains, mutations could be grouped into five classes, specifically flagellin-associated genes, pili-associated genes, heat-shock protein genes, genes related to the glycolytic pathway, and biosynthesis-related genes. Of these mutants, we here focused on the serA mutant, as the association between this gene and penetration activity is yet unknown. Inactivation of the serA gene caused significant repression of bacterial penetration through Caco-2 cell monolayers with decreased swimming and swarming motilities, bacterial adherence, and fly mortality rate, as well as repression of ExoS secretion; however, twitching motility was not affected. Furthermore, L-serine, which is known to inhibit the D-3-phosphoglycerate dehydrogenase activity of the SerA protein, caused significant reductions in penetration through Caco-2 cell monolayers, swarming and swimming motilities, bacterial adherence to Caco-2 cells, and virulence in flies in the wild-type P. aeruginosa PAO1 strain. Together, these results suggest that serA is associated with bacterial motility and adherence, which are mediated by flagella that play a key role in the penetration of P. aeruginosa through Caco-2 cell monolayers. Oral administration of L-serine to compromised hosts might have the potential to interfere with bacterial translocation and prevent septicemia caused by P. aeruginosa through inhibition of serA function.
authors.affiliation: Division of Microbiology, Department of Medical Technology, Kagawa Prefectural University of Health Sciences, Kagawa, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Yasuda
authors.affiliation: Division of Microbiology, Department of Medical Technology, Kagawa Prefectural University of Health Sciences, Kagawa, Japan.
authors.forename: Syouya
authors.initials: S
authors.lastname: Nagata
authors.affiliation: Division of Microbiology, Department of Medical Technology, Kagawa Prefectural University of Health Sciences, Kagawa, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Yamane
authors.affiliation: Division of Microbiology, Department of Medical Technology, Kagawa Prefectural University of Health Sciences, Kagawa, Japan.
authors.forename: Chinami
authors.initials: C
authors.lastname: Kunikata
authors.affiliation: Division of Microbiology, Department of Infectious Medicine, Kurume University School of Medicine, Fukuoka, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Kida
authors.affiliation: Division of Microbiology, Department of Infectious Medicine, Kurume University School of Medicine, Fukuoka, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Kuwano
authors.affiliation: Division of Microbiology, Department of Medical Technology, Kagawa Prefectural University of Health Sciences, Kagawa, Japan.
authors.forename: Chigusa
authors.initials: C
authors.lastname: Suezawa
authors.affiliation: Division of Microbiology, Department of Medical Technology, Kagawa Prefectural University of Health Sciences, Kagawa, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Okuda
mesh_terms: D058947:Bacterial Secretion Systems / Q000235:genetics; D018988:Bacterial Translocation / Q000235:genetics*; D018938:Caco-2 Cells; D005407:Flagella / Q000187:drug effects / Q000378:metabolism; D005798:Genes, Bacterial; D006801:Humans; D009068:Movement; D009154:Mutation / Q000235:genetics; D050543:Phosphoglycerate Dehydrogenase / Q000378:metabolism; D011552:Pseudomonas Infections / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000201:enzymology / Q000235:genetics* / Q000472:pathogenicity; D012694:Serine / Q000494:pharmacology; D014774:Virulence
chemical_list: D058947:Bacterial Secretion Systems; D012694:Serine; D050543:Phosphoglycerate Dehydrogenase