Many mycoplasmas are pathogenic and cause disease in human and animals. M. gallisepticum causes c... more Many mycoplasmas are pathogenic and cause disease in human and animals. M. gallisepticum causes chronic respiratory disease in chickens and infectious sinusitis in turkeys, resulting in economic losses in poultry industries throughout the world. Expanding our knowledge about the pathogenesis of mycoplasma infections requires better understanding of the specific gene functions of these bacteria.
This thesis was scanned from the print manuscript for digital preservation and is copyright the a... more This thesis was scanned from the print manuscript for digital preservation and is copyright the author. Researchers can access this thesis by asking their local university, institution or public library to make a request on their behalf. Monash staff and postgraduate students can use the link in the References field.
Background Abortion in horses leads to economic and welfare losses to the equine industry. Most c... more Background Abortion in horses leads to economic and welfare losses to the equine industry. Most cases of equine abortions are sporadic, and the cause is often unknown. This study aimed to detect potential abortigenic pathogens in equine abortion cases in Australia using metagenomic deep sequencing methods. Results After sequencing and analysis, a total of 68 and 86 phyla were detected in the material originating from 49 equine abortion samples and 8 samples from normal deliveries, respectively. Most phyla were present in both groups, with the exception of Chlamydiae that were only present in abortion samples. Around 2886 genera were present in the abortion samples and samples from normal deliveries at a cut off value of 0.001% of relative abundance. Significant differences in species diversity between aborted and normal tissues was observed. Several potential abortigenic pathogens were identified at a high level of relative abundance in a number of the abortion cases, including Esch...
The zoonotic bacterial pathogen Coxiella burnetii is the causative agent of Q fever, a febrile il... more The zoonotic bacterial pathogen Coxiella burnetii is the causative agent of Q fever, a febrile illness which can cause a serious chronic infection. C. burnetii is a unique intracellular bacterium which replicates within host lysosome-derived vacuoles. The ability of C. burnetii to replicate within this normally hostile compartment is dependent on the activity of the Dot/Icm type 4B secretion system. In a previous study, a transposon mutagenesis screen suggested that the disruption of the gene encoding the novel protein CBU2072 rendered C. burnetii incapable of intracellular replication.
<p>UDP-galactose and GDP-mannose/GDP-arabinose are transported into the Golgi via transport... more <p>UDP-galactose and GDP-mannose/GDP-arabinose are transported into the Golgi via transporters LPG5A/LPG5B <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003402#pntd.0003402-Capul1" target="_blank">[37]</a> and LPG2 <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003402#pntd.0003402-Ma1" target="_blank">[65]</a> respectively. Galactose and mannose-phosphate are cleaved for use in phosphoglycan synthesis. Following cleavage, GMP is exchanged for GDP-mannose transport into the lumen. In the case of UDP, hydrolysis to UMP is catalyzed by NTPD1, allowing efficient ongoing transport of UDP-galactose into the Golgi lumen.</p
is an intracellular Gram-negative bacterium responsible for the important zoonotic disease Q feve... more is an intracellular Gram-negative bacterium responsible for the important zoonotic disease Q fever. Improved genetic tools and the ability to grow this bacterium in host cell-free media has advanced the study of pathogenesis, but the mechanisms that allow it to survive inside the hostile phagolysosome remain incompletely understood. Previous screening of a transposon mutant library for replication within HeLa cells has suggested that , encoding a putative L-aspartate oxidase required for de novo NAD synthesis, is needed for intracellular replication. Here, using genetic complementation of two independent mutants and intracellular replication assays, we confirmed this finding. Untargeted metabolite analyses demonstrated key changes in metabolites in the NAD biosynthetic pathway in the mutant compared with the wildtype, confirming the involvement of NadB in de novo NAD synthesis. Bioinformatic analysis revealed the presence of a functionally conserved arginine residue at position 275....
Microbiology and molecular biology reviews : MMBR, 2008
In humans, purinergic signaling plays an important role in the modulation of immune responses thr... more In humans, purinergic signaling plays an important role in the modulation of immune responses through specific receptors that recognize nucleoside tri- and diphosphates as signaling molecules. Ecto-nucleoside triphosphate diphosphohydrolases (ecto-NTPDases) have important roles in the regulation of purinergic signaling by controlling levels of extracellular nucleotides. This process is key to pathophysiological protective responses such as hemostasis and inflammation. Ecto-NTPDases are found in all higher eukaryotes, and recently it has become apparent that a number of important parasitic pathogens of humans express surface-located NTPDases that have been linked to virulence. For those parasites that are purine auxotrophs, these enzymes may play an important role in purine scavenging, although they may also influence the host response to infection. Although ecto-NTPDases are rare in bacteria, expression of a secreted NTPDase in Legionella pneumophila was recently described. This ect...
The present study shows that the Legionnaire's bacterium harbours two eukaryotic type-NTPDase... more The present study shows that the Legionnaire's bacterium harbours two eukaryotic type-NTPDases that function predominantly as ATPases. The hydrolysis of ATP contributes to the ability of Legionella pneumophila to replicate within an intracellular compartment in eukaryotic cells.
Previously, we identified ladC in a cohort of genes that were present in Legionella pneumophila b... more Previously, we identified ladC in a cohort of genes that were present in Legionella pneumophila but absent in other Legionella species. Here we constructed a ladC mutant of L. pneumophila and assessed its ability to replicate in mammalian cell lines and Acanthamoeba castellanii . The ladC mutant was recovered in significantly lower numbers than wild-type L. pneumophila at early time points, which was reversed upon transcomplementation with ladC but not ladC N430A/R434A , encoding a putative catalytically inactive derivative of the protein. In fact, complementation of ladC ::Km with ladC N430A/R434A resulted in a severe replication defect within human and amoeba cell models of infection, which did not follow a typical dominant negative phenotype. Using differential immunofluorescence staining to distinguish adherent from intracellular bacteria, we found that the ladC mutant exhibited a 10-fold reduction in adherence to THP-1 macrophages but no difference in uptake by THP-1 cells. Whe...
Legionella pneumophila is a ubiquitous environmental organism and a facultative intracellular pat... more Legionella pneumophila is a ubiquitous environmental organism and a facultative intracellular pathogen of humans. To identify genes that may contribute to the virulence of L. pneumophila , we performed genomic subtractive hybridization between L. pneumophila serogroup 1 strain 02/41 and L. micdadei strain 02/42. A total of 144 L. pneumophila -specific clones were sequenced, revealing 151 genes that were absent in L. micdadei strain 02/42. Low-stringency Southern hybridization was used to determine the distribution of 41 sequences, representing 40 open reading frames (ORFs) with a range of putative functions among L. pneumophila isolates of various serogroups as well as strains of Legionella longbeachae , L. micdadei , Legionella gormanii , and Legionella jordanis . Twelve predicted ORFs were L. pneumophila specific, including the gene encoding the dot/icm effector, lepB , as well as several genes predicted to play a role in lipopolysaccharide biosynthesis and cell wall synthesis and...
The environmental pathogen Legionella pneumophila possesses five proteins with Sel1 repeats (SLRs... more The environmental pathogen Legionella pneumophila possesses five proteins with Sel1 repeats (SLRs) from the tetratricopeptide repeat protein family. Three of these proteins, LpnE, EnhC, and LidL, have been implicated in the ability of L. pneumophila to efficiently establish infection and/or manipulate host cell trafficking events. Previously, we showed that LpnE is important for L. pneumophila entry into macrophages and epithelial cells. In further virulence studies here, we show that LpnE is also required for efficient infection of Acanthamoeba castellanii by L. pneumophila and for replication of L. pneumophila in the lungs of A/J mice. In addition, we found that the role of LpnE in host cell invasion is dependent on the eight SLR regions of the protein. A truncated form of LpnE lacking the two C-terminal SLR domains was unable to complement the invasion defect of an lpnE mutant of L. pneumophila 130b in both the A549 and THP-1 cell lines. The lpnE mutant displayed impaired avoidan...
Many mycoplasmas are pathogenic and cause disease in human and animals. M. gallisepticum causes c... more Many mycoplasmas are pathogenic and cause disease in human and animals. M. gallisepticum causes chronic respiratory disease in chickens and infectious sinusitis in turkeys, resulting in economic losses in poultry industries throughout the world. Expanding our knowledge about the pathogenesis of mycoplasma infections requires better understanding of the specific gene functions of these bacteria.
This thesis was scanned from the print manuscript for digital preservation and is copyright the a... more This thesis was scanned from the print manuscript for digital preservation and is copyright the author. Researchers can access this thesis by asking their local university, institution or public library to make a request on their behalf. Monash staff and postgraduate students can use the link in the References field.
Background Abortion in horses leads to economic and welfare losses to the equine industry. Most c... more Background Abortion in horses leads to economic and welfare losses to the equine industry. Most cases of equine abortions are sporadic, and the cause is often unknown. This study aimed to detect potential abortigenic pathogens in equine abortion cases in Australia using metagenomic deep sequencing methods. Results After sequencing and analysis, a total of 68 and 86 phyla were detected in the material originating from 49 equine abortion samples and 8 samples from normal deliveries, respectively. Most phyla were present in both groups, with the exception of Chlamydiae that were only present in abortion samples. Around 2886 genera were present in the abortion samples and samples from normal deliveries at a cut off value of 0.001% of relative abundance. Significant differences in species diversity between aborted and normal tissues was observed. Several potential abortigenic pathogens were identified at a high level of relative abundance in a number of the abortion cases, including Esch...
The zoonotic bacterial pathogen Coxiella burnetii is the causative agent of Q fever, a febrile il... more The zoonotic bacterial pathogen Coxiella burnetii is the causative agent of Q fever, a febrile illness which can cause a serious chronic infection. C. burnetii is a unique intracellular bacterium which replicates within host lysosome-derived vacuoles. The ability of C. burnetii to replicate within this normally hostile compartment is dependent on the activity of the Dot/Icm type 4B secretion system. In a previous study, a transposon mutagenesis screen suggested that the disruption of the gene encoding the novel protein CBU2072 rendered C. burnetii incapable of intracellular replication.
<p>UDP-galactose and GDP-mannose/GDP-arabinose are transported into the Golgi via transport... more <p>UDP-galactose and GDP-mannose/GDP-arabinose are transported into the Golgi via transporters LPG5A/LPG5B <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003402#pntd.0003402-Capul1" target="_blank">[37]</a> and LPG2 <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003402#pntd.0003402-Ma1" target="_blank">[65]</a> respectively. Galactose and mannose-phosphate are cleaved for use in phosphoglycan synthesis. Following cleavage, GMP is exchanged for GDP-mannose transport into the lumen. In the case of UDP, hydrolysis to UMP is catalyzed by NTPD1, allowing efficient ongoing transport of UDP-galactose into the Golgi lumen.</p
is an intracellular Gram-negative bacterium responsible for the important zoonotic disease Q feve... more is an intracellular Gram-negative bacterium responsible for the important zoonotic disease Q fever. Improved genetic tools and the ability to grow this bacterium in host cell-free media has advanced the study of pathogenesis, but the mechanisms that allow it to survive inside the hostile phagolysosome remain incompletely understood. Previous screening of a transposon mutant library for replication within HeLa cells has suggested that , encoding a putative L-aspartate oxidase required for de novo NAD synthesis, is needed for intracellular replication. Here, using genetic complementation of two independent mutants and intracellular replication assays, we confirmed this finding. Untargeted metabolite analyses demonstrated key changes in metabolites in the NAD biosynthetic pathway in the mutant compared with the wildtype, confirming the involvement of NadB in de novo NAD synthesis. Bioinformatic analysis revealed the presence of a functionally conserved arginine residue at position 275....
Microbiology and molecular biology reviews : MMBR, 2008
In humans, purinergic signaling plays an important role in the modulation of immune responses thr... more In humans, purinergic signaling plays an important role in the modulation of immune responses through specific receptors that recognize nucleoside tri- and diphosphates as signaling molecules. Ecto-nucleoside triphosphate diphosphohydrolases (ecto-NTPDases) have important roles in the regulation of purinergic signaling by controlling levels of extracellular nucleotides. This process is key to pathophysiological protective responses such as hemostasis and inflammation. Ecto-NTPDases are found in all higher eukaryotes, and recently it has become apparent that a number of important parasitic pathogens of humans express surface-located NTPDases that have been linked to virulence. For those parasites that are purine auxotrophs, these enzymes may play an important role in purine scavenging, although they may also influence the host response to infection. Although ecto-NTPDases are rare in bacteria, expression of a secreted NTPDase in Legionella pneumophila was recently described. This ect...
The present study shows that the Legionnaire's bacterium harbours two eukaryotic type-NTPDase... more The present study shows that the Legionnaire's bacterium harbours two eukaryotic type-NTPDases that function predominantly as ATPases. The hydrolysis of ATP contributes to the ability of Legionella pneumophila to replicate within an intracellular compartment in eukaryotic cells.
Previously, we identified ladC in a cohort of genes that were present in Legionella pneumophila b... more Previously, we identified ladC in a cohort of genes that were present in Legionella pneumophila but absent in other Legionella species. Here we constructed a ladC mutant of L. pneumophila and assessed its ability to replicate in mammalian cell lines and Acanthamoeba castellanii . The ladC mutant was recovered in significantly lower numbers than wild-type L. pneumophila at early time points, which was reversed upon transcomplementation with ladC but not ladC N430A/R434A , encoding a putative catalytically inactive derivative of the protein. In fact, complementation of ladC ::Km with ladC N430A/R434A resulted in a severe replication defect within human and amoeba cell models of infection, which did not follow a typical dominant negative phenotype. Using differential immunofluorescence staining to distinguish adherent from intracellular bacteria, we found that the ladC mutant exhibited a 10-fold reduction in adherence to THP-1 macrophages but no difference in uptake by THP-1 cells. Whe...
Legionella pneumophila is a ubiquitous environmental organism and a facultative intracellular pat... more Legionella pneumophila is a ubiquitous environmental organism and a facultative intracellular pathogen of humans. To identify genes that may contribute to the virulence of L. pneumophila , we performed genomic subtractive hybridization between L. pneumophila serogroup 1 strain 02/41 and L. micdadei strain 02/42. A total of 144 L. pneumophila -specific clones were sequenced, revealing 151 genes that were absent in L. micdadei strain 02/42. Low-stringency Southern hybridization was used to determine the distribution of 41 sequences, representing 40 open reading frames (ORFs) with a range of putative functions among L. pneumophila isolates of various serogroups as well as strains of Legionella longbeachae , L. micdadei , Legionella gormanii , and Legionella jordanis . Twelve predicted ORFs were L. pneumophila specific, including the gene encoding the dot/icm effector, lepB , as well as several genes predicted to play a role in lipopolysaccharide biosynthesis and cell wall synthesis and...
The environmental pathogen Legionella pneumophila possesses five proteins with Sel1 repeats (SLRs... more The environmental pathogen Legionella pneumophila possesses five proteins with Sel1 repeats (SLRs) from the tetratricopeptide repeat protein family. Three of these proteins, LpnE, EnhC, and LidL, have been implicated in the ability of L. pneumophila to efficiently establish infection and/or manipulate host cell trafficking events. Previously, we showed that LpnE is important for L. pneumophila entry into macrophages and epithelial cells. In further virulence studies here, we show that LpnE is also required for efficient infection of Acanthamoeba castellanii by L. pneumophila and for replication of L. pneumophila in the lungs of A/J mice. In addition, we found that the role of LpnE in host cell invasion is dependent on the eight SLR regions of the protein. A truncated form of LpnE lacking the two C-terminal SLR domains was unable to complement the invasion defect of an lpnE mutant of L. pneumophila 130b in both the A549 and THP-1 cell lines. The lpnE mutant displayed impaired avoidan...
Uploads
Papers by Fiona Sansom