370 research outputs found
Microbial Genomics Raw Sequence and Analysis Data
No full textWe aim to better understand the molecular mechanisms of infectious disease and identify potential therapeutic and diagnostic targets by exploiting next-generation genomic data. A major focus is the comparative analysis of genomes obtained from local clinical isolates (Brisbane & Australia) of important human pathogens such as Escherichia coli, Pseudomonas aeruginosa, Staphylococci, Streptococci, Legionella pneumophila and Acinetobacter baumannii. In particular we are interested in the evolution and mobility of genes encoding virulence factors that are widely conserved amongst bacterial pathogens (e.g., fimbriae, pili and type III and type IV secretion systems and secreted effectors). We have sequenced almost 1,000 bacterial genomes using a variety of different next-generation sequencing technologies (Illumina, SOLiD, 454, PacBio). This collection varies from just sequencing reads right through to annotated complete genomes that we have derived from the data
Regulatory interplay between pap operons in uropathogenic Escherichia coli
No full textPathogenic bacteria have a large repertoire of surface organelles involved in adherence, motility and protein export, but how individual bacteria co-ordinate surface organelle expression to prevent interference and excessive immune stimulation is unclear. Phase variation is a mechanism by which expression of surface factors is limited to a fraction of the bacterial population; however, the presence of multiple homologous surface structures controlled by related mechanisms and regulators antagonizes the independent expression achieved by phase variation. To investigate whether other mechanisms have evolved to sort out the bacterial cell surface, we examined regulatory cross-talk between multiple phase-variable pyelonephritis-associated pili (pap) operons in Escherichia coli isolates associated with urinary tract infections. Allelic variation identified in the regulatory regions and regulators acts synergistically to limit coexpression of homologous fimbrial operons. In particular, there is evidence that papI is under positive selection and PapI variants displayed differences in their capacity to activate related pap operons. Alleles of the high-affinity binding site for PapB were shown to contain a variable number of (T/A)(3) repeats occurring every 9 bp that altered the sensitivity of pap operon activation. Taken together with other examples of surface organelle cross-talk, we illustrate how this regulation could promote sequential expression
A FimH inhibitor prevents acute bladder infection and treats chronic cystitis caused by multidrug resistant uropathogenic Escherichia coli ST131
No full textackground. Escherichia coli O25b:H4-ST131 represents a predominant clone of multidrug-resistant uropathogens currently circulating worldwide in hospitals and the community. Urinary tract infections (UTIs) caused by E. coli ST131 are typically associated with limited treatment options and are often recurrent
UafB is a serine-rich repeat adhesin of Staphylococcus saprophyticus that mediates binding to fibronectin, fibrinogen and human uroepithelial cells
No full textStaphylococcus saprophyticus is an important cause of urinary tract infection (UTI), particularly among young women, and is second only to uropathogenic Escherichia coli as the most frequent cause of UTI. The molecular mechanisms of urinary tract colonization by S. saprophyticus remain poorly understood. We have identified a novel 6.84 kb plasmid-located adhesin-encoding gene in S. saprophyticus strain MS1146 which we have termed uro-adherence factor B (uafB). UafB is a glycosylated serine-rich repeat protein that is expressed on the surface of S. saprophyticus MS1146. UafB also functions as a major cell surface hydrophobicity factor. To characterize the role of UafB we generated an isogenic uafB mutant in S. saprophyticus MS1146 by interruption with a group II intron. The uafB mutant had a significantly reduced ability to bind to fibronectin and fibrinogen. Furthermore, we show that a recombinant protein containing the putative binding domain of UafB binds specifically to fibronectin and fibrinogen. UafB was not involved in adhesion in a mouse model of UTI; however, we observed a striking UafB-mediated adhesion phenotype to human uroepithelial cells. We have also identified genes homologous to uafB in other staphylococci which, like uafB, appear to be located on transposable elements. Thus, our data indicate that UafB is a novel adhesin of S. saprophyticus that contributes to cell surface hydrophobicity, mediates adhesion to fibronectin and fibrinogen, and exhibits tropism for human uroepithelial cells
Easyfig: A genome comparison visualizer
No full textEasyfig is a Python application for creating linear comparison figures of multiple genomic loci with an easy-to-use graphical user interface. BLAST comparisons between multiple genomic regions, ranging from single genes to whole prokaryote chromosomes, can be generated, visualized and interactively coloured, enabling a rapid transition between analysis and the preparation of publication quality figures. © The Author(s) 2011. Published by Oxford University Press
Differential regulation of twitching motility and elastase production by Vfr in Pseudomonas aeruginosa
No full textVfr, a homolog of Escherichia coli cyclic AMP (cAMP) receptor protein, has been shown to regulate quorum sensing, exotoxin A production, and regA transcription in Pseudomonas aeruginosa. We identified a twitching motility-defective mutant that carries a transposon insertion in vfr and confirmed that vfr is required for twitching motility by construction of an independent allelic deletion-replacement mutant of vfr that exhibited the same phenotype, as well as by the restoration of normal twitching motility by complementation of these mutants with wild-type vfr. Vfr-null mutants exhibited severely reduced twitching motility with barely detectable levels of type IV pili, as well as loss of elastase production and altered pyocyanin production. We also identified reduced-twitching variants of quorum-sensing mutants (PAK lasl::Tc) with a spontaneous deletion in vfr (S. A. Beatson, C. B. Whitchurch, A. B. T. Semmler, and J. S. Mattick, J. Bacteriol., 184:3598-3604,2002), the net result of which was the loss of five residues (EQERS) from the putative cAMP-binding pocket or Vfr. This allele (VfrDeltaEQERS) was capable of restoring elastase and pyocyanin production to wild-type levels in vfr-null mutants but not their defects in twitching motility. Furthermore, structural analysis of Vfr and VfrDeltaEQERS in relation to E. coli CRP suggests that Vfr is capable of binding both cAMP and cyclic GMP whereas VfrDeltaEQERS is only capable of responding to cAMP. We suggest that Vfr controls twitching motility and quorum sensing via independent pathways in response to these different signals, bound by the same cyclic nucleotide monophosphate-binding pocket
The principle of Ultra Vires and the local authorities’ decisions in England
No full textThe hypothesis of this thesis is that valid administrative decisions from local authorities are guaranteed via clear and precise enabling clauses in the primary legislation. Taking examples from local government in England, the author argues that the style of drafting local authorities’ legislations influences decisions taken by local authorities - so in attempting to exercise implied powers conferred by the imprecise enabling legislation and insufficient guidance, local authorities tend to go beyond intended legal powers and as a result take unreasonable, arbitrary and invalid decisions
Chaperone-usher fimbriae of Escherichia coli
No full textChaperone-usher (CU) fimbriae are adhesive surface organelles common to many Gram-negative bacteria. Escherichia coli genomes contain a large variety of characterised and putative CU fimbrial operons, however, the classification and annotation of individual loci remains problematic. Here we describe a classification model based on usher phylogeny and genomic locus position to categorise the CU fimbrial types of E. coli. Using the BLASTp algorithm, an iterative usher protein search was performed to identify CU fimbrial operons from 35 E. coli (and one Escherichia fergusonnii) genomes representing different pathogenic and phylogenic lineages, as well as 132 Escherichia spp. plasmids. A total of 458 CU fimbrial operons were identified, which represent 38 distinct fimbrial types based on genomic locus position and usher phylogeny. The majority of fimbrial operon types occupied a specific locus position on the E. coli chromosome; exceptions were associated with mobile genetic elements. A group of core-associated E. coli CU fimbriae were defined and include the Type 1, Yad, Yeh, Yfc, Mat, F9 and Ybg fimbriae. These genes were present as intact or disrupted operons at the same genetic locus in almost all genomes examined. Evaluation of the distribution and prevalence of CU fimbrial types among different pathogenic and phylogenic groups provides an overview of group specific fimbrial profiles and insight into the ancestry and evolution of CU fimbriae in E. coli
Functional and genomic analysis of E. coli that cause urinary tract infection
No full textUropathogenic Escherichia coli (UPEC) is a major cause of urinary tract infections (UTI) and sepsis. Recently, a highly virulent clone of UPEC (E. coli ST131) that is resistant to multiple types of antibiotics has emerged and spread worldwide. This project uses genomic and high-throughput functional analysis methods to understand E. coli ST131 virulence and resistance. The outcomes of the work will be a better understanding of how E. coli ST131 causes disease, and potentially new treatment regimes for UTI.$793,056.00Project GrantsStandard Project Gran
Bacterial Pathogenomics: whole-genome sequencing to investigate infection transmission, pathogenesis and antibiotic resistance
No full textAs bacterial superbugs – resistant to multiple antibiotics – dominate the headlines, the pipeline for new antibiotics has all but dried up. High-throughput DNA sequencing heralds a golden opportunity for infectious disease research. By studying the entire collection of genes - the genome - of large numbers of multidrug resistant bacterial strains, we aim to better understand the genetic changes that govern the emergence and global spread of superbugs and translate these findings into the clinic.$455,452.00Career Development FellowshipsRD Wright Biomedical CD
- …
