title: The role of short-chain dehydrogenase/oxidoreductase, induced by salt stress, on host interaction of B. pseudomallei.
abstract: BACKGROUND
  Burkholderia pseudomallei is the causative agent of melioidosis, a frequently occurring disease in northeastern Thailand, where soil and water high in salt content are common. Using microarray analysis, we previously showed that B. pseudomallei up-regulated a short-chain dehydrogenase/oxidoreductase (SDO) under salt stress. However, the importance of SDO in B. pseudomallei infection is unknown. This study aimed to explore the function of B. pseudomallei SDO, and to investigate its role in interactions between B. pseudomallei and host cells.
  
  
  RESULTS
  Bioinformatics analysis of B. pseudomallei SDO structure, based on homology modeling, revealed a NAD+ cofactor domain and a catalytic triad containing Ser149, Tyr162, and Lys166. This is similar to Bacillus megaterium glucose 1-dehydrogenase. To investigate the role of this protein, we constructed a B. pseudomallei SDO defective mutant, measured glucose dehydrogenase (GDH) activity, and tested the interactions with host cells. The B. pseudomallei K96243 wild type exhibited potent GDH activity under condition containing 300 mM NaCl, while the mutant showed activity levels 15 times lower. Both invasion into the A549 cell line and early intracellular survival within the J774A.1 macrophage cell were impaired in the mutant. Complementation of SDO was able to restore the mutant ability to produce GDH activity, invade epithelial cells, and survive in macrophages.
  
  
  CONCLUSIONS
  Our data suggest that induced SDO activity during salt stress may facilitate B. pseudomallei invasion and affect initiation of successful intracellular infection. Identifying the role of B. pseudomallei SDO provides a better understanding of the association between bacterial adaptation and pathogenesis in melioidosis.
authors.forename: Pornpan
authors.initials: P
authors.lastname: Pumirat
authors.forename: Usa
authors.initials: U
authors.lastname: Boonyuen
authors.forename: Muthita
authors.initials: M
authors.lastname: Vanaporn
authors.forename: Peechanika
authors.initials: P
authors.lastname: Pinweha
authors.forename: Sarunporn
authors.initials: S
authors.lastname: Tandhavanant
authors.forename: Sunee
authors.initials: S
authors.lastname: Korbsrisate
authors.affiliation: Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand. narisara@tropmedres.ac.
authors.forename: Narisara
authors.initials: N
authors.lastname: Chantratita
mesh_terms: D000818:Animals; D001665:Binding Sites; D016957:Burkholderia pseudomallei / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D020134:Catalytic Domain; D002460:Cell Line; D003067:Coenzymes / Q000378:metabolism; D019295:Computational Biology; D004705:Endocytosis; D004847:Epithelial Cells / Q000382:microbiology; D017353:Gene Deletion; D005816:Genetic Complementation Test; D054884:Host-Pathogen Interactions; D006801:Humans; D008264:Macrophages / Q000382:microbiology; D051379:Mice; D050296:Microbial Viability; D009243:NAD / Q000378:metabolism; D009997:Osmotic Pressure; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D012492:Salts / Q000378:metabolism*
chemical_list: D003067:Coenzymes; D012492:Salts; D009243:NAD; D010088:Oxidoreductases