Project description:Transfer RNA (tRNA) modifications play a crucial role in maintaining translational fidelity and efficiency, and they may function as regulatory elements in stress response and virulence. Despite their pivotal roles, a comprehensive mapping of tRNA modifications and their associated synthesis genes is still limited, with a predominant focus on free-living bacteria. In this study, we employed a multidisciplinary approach, incorporating comparative genomics, mass spectrometry, and next-generation sequencing, to predict the set of tRNA modification genes responsible for tRNA maturation in two intracellular pathogens—Bartonella henselae Houston I and Bartonella quintana Toulouse, which are causative agents of cat-scratch disease and trench fever, respectively. This analysis presented challenges, particularly because of host RNA contamination, which served as a potential source of error. However, our approach predicted 26 genes responsible for synthesizing 23 distinct tRNA modifications in B. henselae and 22 genes associated with 23 modifications in B. quintana. Notably, akin to other intracellular and symbiotic bacteria, both Bartonella species have undergone substantial reductions in tRNA modification genes, mostly by simplifying the hypermodifications present at positions 34 and 37. B. quintana exhibited the additional loss of four modifications and these were linked to examples of gene decay, providing snapshots of reductive evolution.
Project description:Studies on S. aureus sub-populations revealed that genomes are well conserved between isolates from the same lineages despite geographic, temporal and selective diversity. However, variation of hundreds of genes can occur between isolates from different lineages and these genes could be involved in interaction with host components. In this study, we aimed to investigate the diversity of secreted virulence factors in human and zoonotic S. aureus isolates from different clonal complexes. We focused on the S. aureus clonal complexes (CC) 8 and CC22 as dominant human lineages, and CC398 as dominant livestock-associated MRSA (LA-MRSA) which is disseminating rapidly. To study the diversity of secreted virulence factors, we compared their extracellular proteomes using label-free LC-MS/MS analysis. A common protein database was created based on DNA sequencing data and PAN genome IDs.
Project description:Proteomic analysis two strains of Bartonella quintana using In-solution digestion followed by Stron Cation Exchange (SCX) and RP nano-LC-MS/MS
Project description:Transcriptional profiling of Bartonella quintana grown on a plate at 28C and 37C for various time points. Comparing each individual sample in cy5 to a pooled mix of all samples in cy3 to preserve a common denominator.
Project description:Antibodies are key to the clearance of Bartonella bacteremia, but the mechanisms and targets of protective antibodies are unknown and bacterial evasion strategies remain elusive. We studied experimental Bartonella taylorii infection of mice, its natural host, and investigated protective immune responses. Clearance of bacteremia depended on specific antibodies that interfere with bacterial attachment to erythrocytes. Accordingly, antibodies were effective in the absence of complement and Fc-receptors. Moreover, they formed independently of B-cell hypermutation and isotype class switch. The cloning of neutralizing monoclonal antibodies (mAbs) led to the identification of the bacterial autotransporter CFA as a protective antibody target, and vaccination against CFA protected against Bartonella bacteremia. MAb binding mapped to a region of CFA that is hypervariable in both human- and mouse-pathogenic Bartonella strains, suggesting mutational antibody evasion. These insights further our understanding of Bartonella immunity and immune evasion and elucidate mechanisms driving high Bartonella prevalence in the wild.
