TY - JOUR
T1 - Virulence differences in Toxoplasma mediated by amplification of a family of polymorphic pseudokinases
AU - Behnke, Michael S.
AU - Khan, Asis
AU - Wootton, John C.
AU - Dubey, Jitender P.
AU - Tang, Keliang
AU - Sibley, L. David
PY - 2011/6/7
Y1 - 2011/6/7
N2 - The population structure of Toxoplasma gondii includes three highly prevalent clonal lineages referred to as types I, II, and III, which differ greatly in virulence in the mouse model. Previous studies have implicated a family of serine/threonine protein kinases found in rhoptries (ROPs) as important in mediating virulence differences between strain types. Here, we explored the genetic basis of differences in virulence between the highly virulent type I lineage and moderately virulent type II based on successful genetic cross between these lineages. Genome-wide association revealed that a single quantitative trait locus controls the dramatic difference in lethality between these strain types. Neither ROP16 nor ROP18, previously implicated in virulence of T. gondii, was found to contribute to differences between types I and II. Instead, the major virulence locus contained a tandem cluster of polymorphic alleles of ROP5, which showed similar protein expression between strains. ROP5 contains a conserved serine/threonine protein kinase domain that includes only part of the catalytic triad, and hence, all members are considered to be pseudokinases. Genetic disruption of the entire ROP5 locus in the type I lineage led to complete attenuation of acute virulence, and complementation with ROP5 restored lethality to WT levels. These findings reveal that a locus of polymorphic pseudokinases plays an important role in pathogenesis of toxoplasmosis in the mouse model.
AB - The population structure of Toxoplasma gondii includes three highly prevalent clonal lineages referred to as types I, II, and III, which differ greatly in virulence in the mouse model. Previous studies have implicated a family of serine/threonine protein kinases found in rhoptries (ROPs) as important in mediating virulence differences between strain types. Here, we explored the genetic basis of differences in virulence between the highly virulent type I lineage and moderately virulent type II based on successful genetic cross between these lineages. Genome-wide association revealed that a single quantitative trait locus controls the dramatic difference in lethality between these strain types. Neither ROP16 nor ROP18, previously implicated in virulence of T. gondii, was found to contribute to differences between types I and II. Instead, the major virulence locus contained a tandem cluster of polymorphic alleles of ROP5, which showed similar protein expression between strains. ROP5 contains a conserved serine/threonine protein kinase domain that includes only part of the catalytic triad, and hence, all members are considered to be pseudokinases. Genetic disruption of the entire ROP5 locus in the type I lineage led to complete attenuation of acute virulence, and complementation with ROP5 restored lethality to WT levels. These findings reveal that a locus of polymorphic pseudokinases plays an important role in pathogenesis of toxoplasmosis in the mouse model.
KW - Copy-number variation
KW - Genetic mapping
KW - Parasite
KW - Quantitative trait locus mapping
UR - http://www.scopus.com/inward/record.url?scp=79959348595&partnerID=8YFLogxK
U2 - 10.1073/pnas.1015338108
DO - 10.1073/pnas.1015338108
M3 - Article
C2 - 21586633
AN - SCOPUS:79959348595
SN - 0027-8424
VL - 108
SP - 9631
EP - 9636
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 23
ER -