Coxiella burnetii: Difference between revisions

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==Current Research==
==Current Research==


Enter summaries of the most recent research here--at least three required
''Enter summaries of the most recent research here--at least three required
''


==References==
==References==

Revision as of 09:39, 3 May 2007

A Microbial Biorealm page on the genus Coxiella burnetii

Classification

Higher order taxa

Domain; Phylum; Class; Order; family [Others may be used. Use NCBI link to find]

Bacteria; Proteobacteria; Gammaproteobacteria; Legionellales; Coxiellaceae; Coxiella

Species

NCBI: Taxonomy

Genus species


Coxiella burnetti

Description and significance

Describe the appearance, habitat, etc. of the organism, and why it is important enough to have its genome sequenced. Describe how and where it was isolated. Include a picture or two (with sources) if you can find them.


QFEVER 1.jpg

  • from National Institute of Allergy and Infectious Diseases


Coxiella burnetti is an obligate intracellular gram negative coccobacillus bacterium that is known to be the main pathogen that causes Q fever in mammals and humans. Harold Cox and MacFarlane Burnet initially identified Q fever as “query fever” in 1935 when a number of infections were found to be from an Australian slaughterhouse. Once the perplexity of this disease was elucidated to be a human infection, the name was properly changed to Q fever. Its global pathogenic effect demonstrates the need for preventive measures to control the rate of infection worldwide and its potential use for bioterrorism. The significance of a completed sequenced genome is the benefit of being able to further understand the mechanisms of pathogenesis and use this knowledge to fight against this infectious disease. Sheep, cattle, and goats are major sources of Coxiella burnetti. The mode of transmission to humans is primarily through waste excretion from infected animals followed by inhalation of contaminated air that contains many of these organisms or through an insect vector. Coxiella burnetti live in a wildlife livestock environment and can withstand heat, dryness, and antibacterial compounds, allowing this bacterium to persist outside the host for an extensively long period of time. It is an acidophile, meaning it tends to surround itself in an environment with low pH. Uniquely enough, it can be endocytosed by a macrophage and complete replication inside the phagolysozyme during its life cycle.

Genome structure

Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence? Does it have any plasmids? Are they important to the organism's lifestyle?

Random shotgun method was used to sequence the genome of Coxiella burnetti. The genome of this organism is attributed by the presence of a single 1,995,281 base-pair circular chromosome and a single 37,393 base-pair QpH1 circular plasmid. In the chromosome, there are 1,022 protein-coding genes found for known proteins, 179 genes for proteins of unknown function, 3 stable rRNAs, and 42 stable tRNAs. Percent of G+C content is approximately 42.6% and percent coding is approximately 89.1% in the chromosome. As for QpH1, there are 11 genes found for known proteins, 5 for proteins of unknown function, and no stable RNAs. 39.3% represents the percent of G+C content and 78.8% is the percent coding in the plasmid.


Examining 20 highly conserved proteins in 16S rRNA gene sequence analysis proved the fundamental phylogenetic difference with the α-proteobacterial Rickettsia organisms and confirmed that Coxiella are truly γ-proteobacterial. In genomic comparison with other similar obligate parasites such as those from Rickettsia, Coxiella were found to contain mobile elements, metabolic and transport capabilities not typically found for the kind of bacteria they are. In addition, 29 insertion sequences were located in the genome; this is noteworthy information because other obligate parasites have very little or none of these elements. A notion that Coxiella burnetti are enduring a genome reduction has been proposed due to the fact that 83 pseudogenes have been identified. Proteins synthesized by this bacteria have a particularly high pI, which may give rise to the acidic environment Coxiella burnetti reside in.

Cell structure and metabolism

Describe any interesting features and/or cell structures; how it gains energy; what important molecules it produces.

Being that Coxiella burnetti is a gram negative bacteria, this distinction marks important properties about the cell structure. Gram negative bacteria have two membranes, an inner and outer membrane. The outer membrane lacks an energy source, but compensates by having porins fused into the membrane. The organism does not have a thick cell wall composed of peptidoglycan like gram positive bacteria. In between the two membranes lies the periplasmic space. Lipopolysaccharides are anchored to the membrane. During its life cycle, phagocytosis brings the bacteria into the cell, where it remains in phagocytic vacuoles and replicates in the phagolysozyme.


Unlike the other obligate parasites, the greater metabolic capacities of Coxiella burnetti permit the bacteria to undergo glycolysis, gluconeogenesis, pentose phosphate pathway, and TCA cycle. The absence of ATP/ADP exchangers in their transport system highlights that they do not have a way to utilize ATP as an energy source.

Ecology

Describe any interactions with other organisms (included eukaryotes), contributions to the environment, effect on environment, etc.

Pathology

How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

Application to Biotechnology

Does this organism produce any useful compounds or enzymes? What are they and how are they used?

Current Research

Enter summaries of the most recent research here--at least three required

References

[Sample reference] Takai, K., Sugai, A., Itoh, T., and Horikoshi, K. "Palaeococcus ferrophilus gen. nov., sp. nov., a barophilic, hyperthermophilic archaeon from a deep-sea hydrothermal vent chimney". International Journal of Systematic and Evolutionary Microbiology. 2000. Volume 50. p. 489-500.


Coxiella burnetii infection (Q fever). American Veterinary Medical Association. 02 May 2007 <http://www.avma.org/reference/zoonosis/zncoxiel2.asp>.


ExPASy. Swiss Institute of Bioinformatics. 02 May 2007 <http://expasy.org/sprot/hamap/COXBU.html>.


Genome Project. <http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?CMD=Add%20to%20Clipboard&DB=genomeprj>.


Q fever. Centers for Disease Control and Prevention. 02 May 2007 <http://0-www.cdc.gov.mill1.sjlibrary.org/ncidod/dvrd/qfever/>.


NIAID Biodefense Image Library. National Institute of Allergy and Infectious Diseases. 02 May 2007 <http://www3.niaid.nih.gov/biodefense/Public/Images.htm>.


Seshadri R, Paulsen IT, Eisen JA, et al. Complete genome sequence of the Q-fever pathogen coxiellaburnetii. PNAS. 2003;100:5455-5460.





Edited by Lisa Leung, student of Rachel Larsen and Kit Pogliano