Tsetse thrombin inhibitor: bloodmeal-induced expression of an anticoagulant in salivary glands and gut tissue of Glossina morsitans morsitans.
The tsetse thrombin inhibitor, a potent and specific low molecular mass (3,530 Da) anticoagulant peptide, was purified previously from salivary gland extracts of Glossina morsitans morsitans (Diptera: Glossinidae). A 303-bp coding sequence corresponding to the inhibitor has now been isolated from a tsetse salivary gland cDNA library by using degenerate oligonucleotide probes. The full-length cDNA contains a 26-bp untranslated segment at its 5' end, followed by a 63-bp sequence corresponding to a putative secretory signal peptide. A 96-bp segment codes for the mature tsetse thrombin inhibitor, whose predicted molecular weight matches that of the purified native protein. Based on its lack of homology to any previously described family of molecules, the tsetse thrombin inhibitor appears to represent a unique class of naturally occurring protease inhibitors. Recombinant tsetse thrombin inhibitor expressed in Escherichia coli and the chemically synthesized peptide are both substantially less active than the purified native protein, suggesting that posttranslational modification(s) may be necessary for optimal inhibitory activity. The tsetse thrombin inhibitor gene, which is present as a single copy in the tsetse genome, is expressed at high levels in salivary glands and midguts of adult tsetse flies, suggesting a possible role for the anticoagulant in both feeding and processing of the bloodmeal.
Cappello
M
M
Department of Pediatrics, Yale University School of Medicine, New Haven, CT 06510, USA.
Li
S
S
Chen
X
X
Li
C B
CB
Harrison
L
L
Narashimhan
S
S
Beard
C B
CB
Aksoy
S
S
D000595:Amino Acid Sequence; D000818:Animals; D000925:Anticoagulants; D058833:Antithrombin Proteins; D000991:Antithrombins / Q000737:chemistry / Q000235:genetics* / Q000494:pharmacology; D001483:Base Sequence; D001769:Blood; D003001:Cloning, Molecular; D018076:DNA, Complementary; D004064:Digestive System / Q000378:metabolism*; D004435:Eating; D004926:Escherichia coli; D005260:Female; D005786:Gene Expression Regulation; D019476:Insect Proteins; D008297:Male; D008969:Molecular Sequence Data; D011679:Pupa; D012333:RNA, Messenger / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000494:pharmacology; D012469:Salivary Glands / Q000378:metabolism*; D013917:Thrombin / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014158:Transcription, Genetic; D014370:Tsetse Flies / Q000235:genetics* / Q000502:physiology
D000925:Anticoagulants; D058833:Antithrombin Proteins; D000991:Antithrombins; D018076:DNA, Complementary; D019476:Insect Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; C116164:tsetse thrombin inhibitor; D013917:Thrombin