Helicobacter pylori: Difference between revisions
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The motility of the ''H. pylori'' depends on the flagellar motor driven by the proton motive force. ''H.pylori'' is found in microaerobic (low O2) conditions, although it adapts to high O2 at higher culture densities. It has a inner membrane, and a outer membrane with lipopolysaccharide in the outer leaflet, cell wall and periplasm. | The motility of the ''H. pylori'' depends on the flagellar motor driven by the proton motive force. ''H.pylori'' is found in microaerobic (low O2) conditions, although it adapts to high O2 at higher culture densities. It has a inner membrane, and a outer membrane with lipopolysaccharide in the outer leaflet, cell wall and periplasm. | ||
''H. pylori'' uses the enzyme urease to convert urea in to ammonia and bicarbonate to counteract the low acidity of the stomach. It creates the pH level into a neutralized environment around ''H. pylori'' so that it can survive in the stomach. The defense of the body cannot fight ''H. pylori'' because killer T cells and white cells cannot easily get through the lining of the stomach. As the defense cells die, the ''H. pylori'' feed off the superoxide radicals on the stomach lining of the cells. | |||
''H. pylori'' increases its diversity by the changes in acidity, nutrient availbility, and gastric epithilium. | |||
Revision as of 05:12, 2 May 2007
Classification
Higher order taxa
Bacteria (Domain); Proteobacteria (Phylum); Epsilon Proteobacteria (Class); Campylobacterales (Order); Helicobacteraceae (Family); Helicobacter (Genus)
Genus
Helicobacter pylori
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NCBI: Taxonomy |
Description and significance
Helicobacter pylori is a bacterium that is commonly found in the mucosal lining of the stomach and duodenum that can cause peptic ulcers and gastritis and may lead to gastric cancer and gastric MALT lymphoma (mucosa-associated lymphoid tissue).
H.pylori is a Gram-negative organism that has a 'helical' shaped body with about 6 to 8 flagella at one end. It is found in a very acidic environment, a pH of 2.0 or less in the lining of the stomach and the duodenum. Under stressful environment conditions, the helical shape of the bacteria will change into a coccoid form.
By following the Koch's postulates, H.pylori was discovered by Dr. Robin Warren and Barry Marshall in 1983 that this organism was related to peptic ulcers.
Helicobacter pylori was initially named Campylobacter pylordis because under the microscopy, it showed similar appearances with the campylobacter, but after DNA sequencing, H.pylori was separated into its own genus Helicobacter in 1989. The Helicobacter reflects to the appearances of the organism, helical in vivo, but often rodlike in vitro.
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.
Genome structure
Helicobacter pylori measures about 2-4 micrometers by 0.5-1.0 micrometers. It has a circular shaped genome of 1,667,867 base pairs and 1,590 are predicted for coding sequences, and 300 of which encodes for membrance proteins. The genome contains sequences that encodes for membrane proteins such as the F1F0 ATP synthase complex, and various oxidoreductases, such as cytochrome o, some transporters and 2 component signaling systems. Sequences shows that H.pylori obtains a good-developed system for motility, and DNA restriction and modification.
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?
Cell structure and metabolism
The motility of the H. pylori depends on the flagellar motor driven by the proton motive force. H.pylori is found in microaerobic (low O2) conditions, although it adapts to high O2 at higher culture densities. It has a inner membrane, and a outer membrane with lipopolysaccharide in the outer leaflet, cell wall and periplasm.
H. pylori uses the enzyme urease to convert urea in to ammonia and bicarbonate to counteract the low acidity of the stomach. It creates the pH level into a neutralized environment around H. pylori so that it can survive in the stomach. The defense of the body cannot fight H. pylori because killer T cells and white cells cannot easily get through the lining of the stomach. As the defense cells die, the H. pylori feed off the superoxide radicals on the stomach lining of the cells.
H. pylori increases its diversity by the changes in acidity, nutrient availbility, and gastric epithilium.
Describe any interesting features and/or cell structures; how it gains energy; what important molecules it produces.
Ecology
Describe any interactions with other organisms (included eukaryotes), contributions to the environment, effect on environment, etc.
Pathology
Helicobacter pylori is known for peptic ulcers and gastritis. The organism weakens the protective mucous coating of the stomach and allows acid to get through to the sensitive lining. The bacteria and the acid irritates the lining of the stomach and causes a ulcer. It is common to humans, and animals. H.pylori is able to adapt and survive in the stomach acid which is very acidic because it secretes enzymes that neutralize the acid. This allows the spiral shape bacteria to burrow through the lining.
There are 6 virulence factors in H.pylori. 2 of the 6 factors are the structural parts of the bacterium (flagella, adhesins) and the other 4 factors are the extracellular products: urease, cytotoxins, mucin-degrading proteases and an acid secreation-inhibiting protein.
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
NCBI Genome Project Helicobacter pylori: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9252185&dopt=Abstract
NCBI Genome Project: Helicobacter pylori: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=genomeprj&cmd=Retrieve&dopt=Overview&list_uids=233
Edited by Katherine Park , student of Rachel Larsen and Kit Pogliano
