Helicobacter pylori
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). Helicobacter is a genus of proteobacteria that is found in a very acidic environment, a pH of 2.0 or less in the lining of the stomach and the duodenum.
H.pylori is a Gram-negative organism that has a spiral-rod shaped body with about 6 to 8 flagella at one end. 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, but after DNA sequencing, H.pylori was separated into its own genus Helicobacter in 1989.
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. Because of the large number of genome sequence encoding membrane proteins, the adaption of H.pylori has the ability to live in a positive inside-membrane potential in low pH.
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.
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.
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
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9252185&dopt=Abstract
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
