The role of short-chain dehydrogenase/oxidoreductase, induced by salt stress, on host interaction of B. pseudomallei

Pornpan Pumirat,Peechanika Pinweha,Narisara Chantratita,Sarunporn Tandhavanant,Usa Boonyuen,Muthita Vanaporn,Sunee Korbsrisate

doi:10.1186/1471-2180-14-1

The role of short-chain dehydrogenase/oxidoreductase, induced by salt stress, on host interaction of B. pseudomallei

Pornpan Pumirat, Peechanika Pinweha + Show 5 more

Open Access

https://doi.org/10.1186/1471-2180-14-1

Copy DOI

Abstract

BackgroundBurkholderia 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.ResultsBioinformatics 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.ConclusionsOur 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.

Highlights

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
An earlier study demonstrated that the killing efficiency of Burkholderia species, including B. pseudomallei, against the nematode Caenorhabditis elegans is enhanced in condition containing 300 mM NaCl [10]
We showed that B. pseudomallei grown under salt stress invades a lung epithelial cell line A549 [11] more efficiently, and exhibits significantly greater resistance to ceftazidime, an antibiotic used to treat melioidosis [12]

Summary

Introduction

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. 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. 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. The role of SDO for B. pseudomallei adaptation to osmotic or salt stress remains unknown

Objectives

Methods

Results

Conclusion