Proteomic examination of Leishmania chagasi plasma membrane proteins: Contrast between avirulent and virulent (metacyclic) parasite forms.
OBJECTIVE
About two million new cases of leishmaniasis with 50 000 associated deaths occur worldwide each year. Promastigotes of the causative Leishmania spp. develop from the procyclic stage to the highly virulent metacyclic stage within the sand fly vector. We hypothesized that proteins important for promastigote virulence might be uniquely represented in the plasma membrane of metacyclic, but not procyclic, promastigotes.


METHODS
Procyclic (logarithmic) promastigotes and purified metacyclic promastigotes from stationary phase cultures of Leishmania chagasi were used to prepare membrane preparations either by surface biotinylation-streptavidin affinity separation or by octyl glucoside detergent extraction.


RESULTS
These membrane fractions were enriched over 130- and 250-fold, respectively, as estimated by Western blotting for the plasma membrane's major surface protease. Hundreds or dozens of proteins were identified by LC-MS/MS in the surface biotinylation or detergent extraction, respectively. Confocal microscopy suggested the difference between the lists was due to the fact that proteins localized both on the surface membrane and within the flagellar pocket were accessible to surface biotinylation, whereas only proteins on the membrane were obtained by detergent extraction. Using detergent extraction, we found different proteins were present in membranes of the procyclic stage compared to metacyclic stage promastigotes. Several dozen were stage specific.


CONCLUSIONS
These data provide a foundation for identifying virulence factors in the plasma membranes of Leishmania spp. promastigotes during metacyclogenesis.
Department of Internal Medicine, University of Iowa, Iowa City, USA. cyao@uwyo.edu
Chaoqun
C
Yao
Yalan
Y
Li
John E
JE
Donelson
Mary E
ME
Wilson
D019921:Biotinylation; D002462:Cell Membrane / Q000378:metabolism*; D005591:Chemical Fractionation; D005407:Flagella / Q000378:metabolism; D005786:Gene Expression Regulation; D005960:Glucosides / Q000378:metabolism; D007891:Leishmania / Q000166:cytology / Q000378:metabolism* / Q000472:pathogenicity*; D008565:Membrane Proteins / Q000302:isolation & purification / Q000378:metabolism*; D040901:Proteomics / Q000379:methods*; D015800:Protozoan Proteins / Q000302:isolation & purification / Q000378:metabolism*; D019809:Streptavidin / Q000378:metabolism; D014774:Virulence
D005960:Glucosides; D008565:Membrane Proteins; D015800:Protozoan Proteins; C018619:octyl-beta-D-glucoside; D019809:Streptavidin