Project description:ATP binding cassette (ABC) systems are responsible for the import and export of a wide variety of molecules across cell membranes and comprise one of largest protein superfamilies found in prokarya, eukarya and archea. ABC systems play important roles in bacterial lifestyle, virulence and survival. In this study, an inventory of the ABC systems of Burkholderia pseudomallei strain K96243 and Burkholderia mallei strain ATCC 23344 has been compiled using bioinformatic techniques.The ABC systems in the genomes of B. pseudomallei and B. mallei have been reannotated and subsequently compared. Differences in the number and types of encoded ABC systems in belonging to these organisms have been identified. For example, ABC systems involved in iron acquisition appear to be correlated with differences in genome size and lifestyles between these two closely related organisms.The availability of complete inventories of the ABC systems in B. pseudomallei and B. mallei has enabled a more detailed comparison of the encoded proteins in this family. This has resulted in the identification of ABC systems which may play key roles in the different lifestyles and pathogenic properties of these two bacteria. This information has the potential to be exploited for improved clinical identification of these organisms as well as in the development of new vaccines and therapeutics targeted against the diseases caused by these organisms.
Project description:Prokaryotic cell transcriptomics has been limited to mixed or sub-population dynamics and individual cells within heterogeneous populations, which has hampered further understanding of spatiotemporal and stage-specific processes of prokaryotic cells within complex environments. Here we develop a 'TRANSITomic' approach to profile transcriptomes of single Burkholderia pseudomallei cells as they transit through host cell infection at defined stages, yielding pathophysiological insights. We find that B. pseudomallei transits through host cells during infection in three observable stages: vacuole entry; cytoplasmic escape and replication; and membrane protrusion, promoting cell-to-cell spread. The B. pseudomallei 'TRANSITome' reveals dynamic gene-expression flux during transit in host cells and identifies genes that are required for pathogenesis. We find several hypothetical proteins and assign them to virulence mechanisms, including attachment, cytoskeletal modulation, and autophagy evasion. The B. pseudomallei 'TRANSITome' provides prokaryotic single-cell transcriptomics information enabling high-resolution understanding of host-pathogen interactions.
Project description:We report a case of melioidosis in China and offer a comparison of 5 commercial detection systems for Burkholderia pseudomallei. The organism was misidentified by the VITEK 2 Compact, Phoenix, VITEK mass spectrometry, and API 20NE systems but was eventually identified by the Bruker Biotyper system and 16S rRNA sequencing.
Project description:This study reports the expression profile of intracellular B. pseudomallei following infection of human macrophage-like U937 cells. The transcriptome of intracellular B. pseudomallei harvested from macrophage cells over an infection period of 6 hr (1, 2, 4 and 6 hr post-infection) were compared to in vitro grown bacteria to identify genes whose expression is altered in response to intracellular growth.
Project description:BACKGROUND:The ability of Burkholderia pseudomallei to survive in water likely contributes to its environmental persistence in endemic regions. To determine the physiological adaptations which allow B. pseudomallei to survive in aqueous environments, we performed microarray analyses of B. pseudomallei cultures transferred from Luria broth (LB) to distilled water. FINDINGS:Increased expression of a gene encoding for a putative membrane protein (BPSL0721) was confirmed using a lux-based transcriptional reporter system, and maximal expression was noted at approximately 6 hrs after shifting cells from LB to water. A BPSL0721 deficient mutant of B. pseudomallei was able to survive in water for at least 90 days indicating that although involved, BPSL0721 was not essential for survival. BPSL2961, a gene encoding a putative phosphatidylglycerol phosphatase (PGP), was also induced when cells were shifted to water. This gene is likely involved in cell membrane biosynthesis. We were unable to construct a PGP mutant suggesting that the gene is not only involved in survival in water but is essential for cell viability. We also examined mutants of polyhydroxybutyrate synthase (phbC), lipopolysaccharide (LPS) oligosaccharide and capsule synthesis, and these mutations did not affect survival in water. LPS mutants lacking outer core were found to lose viability in water by 200 days indicating that an intact LPS core provides an outer membrane architecture which allows prolonged survival in water. CONCLUSION:The results from these studies suggest that B. pseudomallei survival in water is a complex process that requires an LPS molecule which contains an intact core region.
Project description:BackgroundBurkholderia pseudomallei is a facultative intracellular pathogen of phagocytic and non-phagocytic cells. How the bacterium interacts with host macrophage cells is still not well understood and is critical to appreciate the strategies used by this bacterium to survive and how intracellular survival leads to disease manifestation.ResultsHere we report the expression profile of intracellular B. pseudomallei following infection of human macrophage-like U937 cells. During intracellular growth over the 6 h infection period, approximately 22 % of the B. pseudomallei genome showed significant transcriptional adaptation. B. pseudomallei adapted rapidly to the intracellular environment by down-regulating numerous genes involved in metabolism, cell envelope, motility, replication, amino acid and ion transport system and regulatory function pathways. Reduced expression in catabolic and housekeeping genes suggested lower energy requirement and growth arrest during macrophage infection, while expression of genes encoding anaerobic metabolism functions were up regulated. However, whilst the type VI secretion system was up regulated, expression of many known virulence factors was not significantly modulated over the 6hours of infection.ConclusionsThe transcriptome profile described here provides the first comprehensive view of how B. pseudomallei survives within host cells and will help identify potential virulence factors and proteins that are important for the survival and growth of B. pseudomallei within human cells.
Project description:A PCR procedure for the discrimination of Burkholderia mallei and Burkholderia pseudomallei was developed. It is based on the nucleotide difference T 2143 C (T versus C at position 2143) between B. mallei and B. pseudomallei detected in the 23S rDNA sequences. In comparison with conventional methods the procedure allows more rapid identification at reduced risk for infection of laboratory personnel.