Schistosoma mansoni: protein phosphorylation during transformation of cercariae to schistosomula.
Infectivity of the multicellular pathogen Schistosoma mansoni for the human host is dependent upon the ability of free-living cercariae to transform rapidly into parasitic schistosomula. The biochemical pathways that regulate this transitional period are unknown. The role of protein phosphorylation was investigated by examining the incorporation of [32Pi]phosphate into proteins of S. mansoni. A sevenfold increase in total phosphorylation was found in 3-hr-old schistosomula as compared to cercariae. Analysis of radiolabeled proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography demonstrated that a 14-kDa protein served as a marker for transformation, being phosphorylated in schistosomula but not cercariae. The protein was phosphorylated on a serine residue. Phosphorylation was stimulated by a shift of parasites from water to salt-containing medium at 23 degrees C. Incubation of organisms in water at 37 degrees C did not initiate phosphorylation of this protein. The 14-kDa phosphoprotein was extracted from parasite homogenates with 1 M NaCl but was insoluble in 1% Triton X-100. Protein phosphorylation during the cercarial-schistosomula transformation may represent an important biochemical event that regulates infectivity of the parasite for the human host.
Wiest
P M
PM
Program in Geographic Medicine, Brown University, Miriam Hospital, Providence, Rhode Island 02906.
Olds
G R
GR
Bowen
W D
WD
D000818:Animals; D003470:Culture Media; D000242:Cyclic AMP / Q000378:metabolism; D015801:Helminth Proteins / Q000737:chemistry / Q000378:metabolism*; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D010768:Phosphoserine / Q000032:analysis; D010830:Physostigmine / Q000494:pharmacology; D011494:Protein Kinases / Q000378:metabolism; D012550:Schistosoma mansoni / Q000254:growth & development / Q000378:metabolism*; D013696:Temperature
D003470:Culture Media; D015801:Helminth Proteins; D010750:Phosphoproteins; D010768:Phosphoserine; D010830:Physostigmine; D000242:Cyclic AMP; D011494:Protein Kinases