TsetseEP, a gut protein from the tsetse Glossina morsitans, is related to a major surface glycoprotein of trypanosomes transmitted by the fly and to the products of a Drosophila gene family.
African trypanosomes live in the lumen of the gut of tsetse (Glossina) and may have to face an immune response. As yet, it is unclear whether they are sensitive to antimicrobial peptides in vivo, but for some years there has been indirect evidence that one or more lectins can influence the infection. We have purified a protein complex from midgut extracts that, by SDS-PAGE, is a doublet of 37 and 38 kDa in a ratio of 3:1. Through prediction from corresponding cDNA clones, the full-length protein (tsetseEP) contains 320 amino acids, including a signal peptide. There is apparently only one gene encoding this protein. Towards the C terminus, the protein contains a run of 59 (EP) repeats, which surprisingly is what comprises almost the entire mature EP procyclin molecule present on the surface of trypanosomes in the tsetse gut. Drosophila contains a number of genes encoding proteins, of unknown function, with the same cysteine pattern as tsetseEP; this pattern is not reported for any other protein. Immunoblotting with a monoclonal antibody against (EP) repeats reveals expression in the gut, but not salivary glands, of female and male flies, whether or not fed. Immunoelectron microscopy shows the presence in vesicles in midgut cells and in the lumen of the gut. Attempts to demonstrate lectin activity were thwarted by limited availability of the protein complex.
Chandra
Manosree
M
Wellcome Centre for Molecular Parasitology, University of Glasgow, 56 Dumbarton Road, Glasgow G11 6NU, UK.
Liniger
Matthias
M
Tetley
Laurence
L
Roditi
Isabel
I
Barry
J David
JD
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018076:DNA, Complementary / Q000235:genetics; D004064:Digestive System / Q000737:chemistry / Q000648:ultrastructure; D004330:Drosophila / Q000235:genetics; D029721:Drosophila Proteins / Q000235:genetics; D017344:Genes, Insect; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*; D007303:Insect Vectors / Q000737:chemistry / Q000235:genetics / Q000469:parasitology; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D005810:Multigene Family; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*; D017386:Sequence Homology, Amino Acid; D014346:Trypanosoma brucei brucei / Q000737:chemistry* / Q000235:genetics; D014370:Tsetse Flies / Q000737:chemistry* / Q000235:genetics / Q000469:parasitology* / Q000648:ultrastructure
D018076:DNA, Complementary; D029721:Drosophila Proteins; D019476:Insect Proteins; D008562:Membrane Glycoproteins; D015800:Protozoan Proteins