Porphyromonas gingivalis
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Classification
Higher order taxa
Domain:Bacteria
Phylum:Bacteroidetes
Class:Bacteroides
Genus:Porphyromonas gingivalis
Species
Genus species:Porphyromonas gingivalis
Description and significance
Porphyromonas gingivalis is an anaerobic, gram negative bacterium that can be found within the mouth of an individual. It is observed to be non-motile and rod-shaped. This bacterium is the principal source of periodontal disease. It has been found that in addition to causing human infections, this bacterium also causes much of the antibiotic resistance problems found today.[1] The way which it operates is very unique, since it is a gram negative bacteria, it can attach to the subgingival coating of the tooth, and it will substitute the gram positive bacteria that is originally there with its own thus causing an inflammation which will disengage the gums from the teeth. When colonized on blood agar it forms black spots. It is important to sequence the genome of this organism because it is found in many locations within the body not only in the oral cavity also in the gastrointestinal tract, respiratory tract and in the colon, this has many consequences. It has been ascertain that periodontal disease is associated with cardiovascular diseases [2] This bacterium is associated with Treptonema denticola and Bacteroides forsythus [3]
Genome structure
The genome of p. gingivalis is circular and its origin of replication is located at oriC which is juxtaposed by the genes dnaA and PG1949. The guanine and cytosine nucleotides make up approximately 49%. At the present, 2,015 genes have been acknowledged with a total of 23,43,479 nucleotides. It has been found that the genome of p. gingivalis is similar to that of Bacteroides thetaiotaomicron, and B.fragilis within the Cytophaga-Flavobacteria-Bacteroides genome. In addition, it closely resembles the genomes of Chlorobium tepidum, and thus this demonstrates the notion that the phyla of Chlorobia and Cytophaga-Flavobacteria-Bacteroides are associated with one another. It has been discovered using genome analysis that this bacterium can metabolize a range of amino acids which will form different metabolic end products that are lethal to the host which is usually human, as well as harming the host’s gingival tissues, thus causing the expansion of periodontal disease. [4] It is found that the size of the genome of P. gingivalis is 2.34 mega bases. In addition, the sequencing of the entire genome is important to be able to determine if there are more medical effects of the bacterium in addition to periodontal disease. Researchers want to be able to establish mechanisms for the virulence as well as vaccines. The goals of this project include, the DNA sequence for the genome; analyzing and interpreting the sequence for the W83 strain; integrate the information that was obtained by the interpreted sequences and compare it with the experimental data from the P. gingivalis research community; finally the purpose of the genome sequences is to be able to make clones, reagents, and information to the research community available.[5]
Cell structure and metabolism
The P.gingivalis is a gram-negative, non-motile, rod-shaped, anaerobic organism. To function, it undergoes a mechanism in which it binds to the subgingival layer of the mouth using fimbriae. These fimbriae not only aid in the role of adhesion but are also found to be pathogenic to the immune system. [6] P. gingivalis takes part in Iron Transport, the way it does this is by using a hemin as a device to help it transport iron. When this builds up it results in the black pigmentation that is detected. To bring the hemin iron complex into the cell it uses an ABC Transporter. In regards to the metabolism P. gingivalis, it can undergo many different types such as:
Carbohydrate Metabolism:
Glycolysis / Gluconeogenesis
Citrate cycle (TCA cycle)
Pentose phosphate cycle
Pentose and glucuronate interconversions
Fructose and mannose metabolism
Galactose metabolism
Ascorbate and aldarate metabolism
Pyruvate metabolism
Glyoxylate and dicarboxylate metabolism
Propanoate metabolism
Butanoate metabolism
C5-Branched dibasic acid metabolism
Energy Metabolism:
Oxidative phosphorylation
ATP synthase
Methane metabolism
Carbon fixation
Reductive carboxylate cycle (CO2 fixation)
Nitrogen metabolism
Sulfur metabolism
Lipid Metabolism:
Fatty acid biosynthesis
Fatty acid metabolism
Synthesis and degradation of ketone bodies
Sterol biosynthesis
Bile acid biosynthesis
C21-Steroid hormone metabolism
Androgen and estrogen metabolism
Nucleotide Metabolism:
Purine metabolism
Pyrimidine metabolism
Nucleotide sugars metabolism
Amino Acid Metabolism:
Glutamate metabolism
Alanine and aspartate metabolism
Glycine, serine and threonine metabolism
Methionine metabolism
Cysteine metabolism
Valine, leucine and isoleucine degradation
Valine, leucine and isoleucine biosynthesis
Lysine biosynthesis
Lysine degradation
Arginine and proline metabolism
Histidine metabolism
Tyrosine metabolism
Phenylalanine metabolism
Tryptophan metabolism
Phenylalanine, tyrosine and tryptophan biosynthesis
Urea cycle and metabolism of amino groups
Metabolism of Other Amino Acids:
beta-Alanine metabolism
Taurine and hypotaurine metabolism
Aminophosphonate metabolism
Selenoamino acid metabolism
Cyanoamino acid metabolism
D-Glutamine and D-glutamate metabolism
D-Arginine and D-ornithine metabolism
D-Alanine metabolism
Glutathione metabolism
Metabolism of Complex Carbohydrates:
Starch and sucrose metabolism
Biosynthesis and degradation of glycoprotein
Aminosugars metabolism
Lipopolysaccharide biosynthesis
Peptideglycan biosynthesis
Glycosaminoglycan degradation
Metabolism of Complex Lipids:
Glycerolipid metabolism
Inositol phosphate metabolism
Sphingophospholipid biosynthesis
Phospholipid degradation
Sphingoglycolipid metabolism
Prostaglandin and leukotriene metabolism
Metabolism of Cofactors and Vitamins:
Thiamine metabolism
Riboflavin metabolism
Vitamin B6 metabolism
Nicotinate and nicotinamide metabolism
Pantothenate and CoA biosynthesis
Biotin metabolism
Folate biosynthesis
One carbon pool by folate
Retinol metabolism
Porphyrin and chlorophyll metabolism
Ubiquinone biosynthesis
Ecology
The organism P. gingivalis is usually found in the orifice of mammals usually humans. It is associated with Treptonema denticola and Bacteroides forsythus. There is no valid evidence that the relationship is symbiotic, but is still under researched theory. It contributes to the formation of gingivitis which is a periodontal disease.
Pathology
The bacteria, P. gingivalis, in addition to others causes gingivitis as well as periodontis. Gingivitis is "A disorder involving inflammation of the gums; may affect surrounding and supporting structures of the teeth." [7] Periodontis is "inflammatory reaction of the tissues surrounding a tooth (periodontium), usually resulting from the extension of gingival inflammation into the periodontium." [8] When a gathering of gram-negative, anaerobic bacteria is observed on the gums, it develops a biofilm called plaque on the tooth. Such bacteria as P. gingivalis and Actinobacillus actinomycetemcomitans are examples. Thus P. gingivalis expresses proteolytic enzymes which regulate the protein function in the body [9]these enzymes that are usually utilized for Cysteine and Arginine metabolism. However, here they affect the link between the tooth and the bone, thus ultimately separating the two from one another, which causes the taking apart of the tooth from jaw. [10]
Symptoms include:[11]
Swelling, redness, and pain in the gums
Bad Breath
Gums fail to have structure
Inflammation of gums
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
1. <|Disease Database>
2. <| Wikipedia>
3.ScienceDaily 6 July 2007. 2 April 2008 <http://www.sciencedaily.com /releases/2007/07/070703171912.htm>.