Genotypic differences in the Chlamydia pneumoniae tyrP locus related to vascular tropism and pathogenicity.
Chlamydia pneumoniae is an obligate intracellular pathogen that causes respiratory infections and has been associated with cardiovascular disease. We compared respiratory and cardiovascular isolates to find genetic differences associated with pathogenicity. A polymorphic region encoding a tyrosine/tryptophan permease was found to differ between disease isolates. Respiratory strains contained multiple copies of the tyrP gene, and vascular strains contained a single copy. Single-nucleotide polymorphism analysis revealed the duplication to be a phylogenetically old event. Gene amplification was associated with higher mRNA levels and higher uptake of the substrate tyrosine, indicating an amino-acid transport-related phenotype associated with the tyrP genotype. Vascular strains, despite their reduced ability to transport tyrosine, do not appear to have a reduced growth rate in vitro. We hypothesize that the important difference between strains of vascular and respiratory origin may lie in the increased tendency of vascular strains to elicit persistent infection that is triggered by amino-acid starvation.
Gieffers
Jens
J
Laboratory of Intracellular Parasites, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA. jens.gieffers@hygiene.ukl.mu-luebeck.de.
Durling
Luke
L
Ouellette
Scot P
SP
Rupp
Jan
J
Maass
Matthias
M
Byrne
Gerald I
GI
Caldwell
Harlan D
HD
Belland
Robert J
RJ
D026905:Amino Acid Transport Systems / Q000235:genetics* / Q000378:metabolism; D001808:Blood Vessels / Q000382:microbiology*; D002318:Cardiovascular Diseases / Q000382:microbiology; D002460:Cell Line; D016993:Chlamydophila pneumoniae / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D003470:Culture Media; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D005838:Genotype; D006367:HeLa Cells; D006801:Humans; D011110:Polymorphism, Genetic; D020641:Polymorphism, Single Nucleotide; D012137:Respiratory System / Q000382:microbiology*; D012141:Respiratory Tract Infections / Q000382:microbiology; D014443:Tyrosine / Q000378:metabolism; D014774:Virulence
D026905:Amino Acid Transport Systems; D003470:Culture Media; D029968:Escherichia coli Proteins; D014443:Tyrosine; C035131:TnaB protein, E coli