Back to Search
Start Over
S-adenosylmethionine transport in Rickettsia prowazekii.
- Source :
-
Journal of bacteriology [J Bacteriol] 2003 May; Vol. 185 (10), pp. 3031-5. - Publication Year :
- 2003
-
Abstract
- Rickettsia prowazekii, the causative agent of epidemic typhus, is an obligate, intracellular, parasitic bacterium that grows within the cytoplasm of eucaryotic host cells. Rickettsiae exploit this intracellular environment by using transport systems for the compounds available in the host cell's cytoplasm. Analysis of the R. prowazekii Madrid E genome sequence revealed the presence of a mutation in the rickettsial metK gene, the gene encoding the enzyme responsible for the synthesis of S-adenosylmethionine (AdoMet). Since AdoMet is required for rickettsial processes, the apparent inability of this strain to synthesize AdoMet suggested the presence of a rickettsial AdoMet transporter. We have confirmed the presence of an AdoMet transporter in the rickettsiae which, to our knowledge, is the first bacterial AdoMet transporter identified. The influx of AdoMet into rickettsiae was a saturable process with a K(T) of 2.3 micro M. Transport was inhibited by S-adenosylethionine and S-adenosylhomocysteine but not by sinfungin or methionine. Transport was also inhibited by 2,4-dinitrophenol, suggesting an energy-linked transport mechanism, and by N-ethylmaleimide. AdoMet transporters with similar properties were also identified in the Breinl strain of R. prowazekii and in Rickettsia typhi. By screening Escherichia coli clone banks for AdoMet transport, the R. prowazekii gene coding for a transporter, RP076 (sam), was identified. AdoMet transport in E. coli containing the R. prowazekii sam gene exhibited kinetics similar to that seen in rickettsiae. The existence of a rickettsial transporter for AdoMet raises intriguing questions concerning the evolutionary relationship between the synthesis and transport of this essential metabolite.
- Subjects :
- Adenosine pharmacology
Bacterial Proteins drug effects
Biological Transport drug effects
Carrier Proteins drug effects
Carrier Proteins genetics
Carrier Proteins metabolism
Cloning, Molecular
Escherichia coli genetics
Ethionine pharmacology
Ethylmaleimide pharmacology
Methionine pharmacology
Rickettsia prowazekii drug effects
Rickettsia prowazekii genetics
S-Adenosylhomocysteine pharmacology
Adenosine analogs & derivatives
Anion Transport Proteins genetics
Anion Transport Proteins metabolism
Bacterial Proteins genetics
Bacterial Proteins metabolism
Ethionine analogs & derivatives
Rickettsia prowazekii metabolism
S-Adenosylmethionine metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0021-9193
- Volume :
- 185
- Issue :
- 10
- Database :
- MEDLINE
- Journal :
- Journal of bacteriology
- Publication Type :
- Academic Journal
- Accession number :
- 12730161
- Full Text :
- https://doi.org/10.1128/JB.185.10.3031-3035.2003