Ms. Cupp et al., ANALYSES OF CDNA AND RECOMBINANT PROTEIN FOR A POTENT VASOACTIVE PROTEIN IN SALIVA OF A BLOOD-FEEDING BLACK FLY, SIMULIUM-VITTATUM, Journal of Experimental Biology, 201(10), 1998, pp. 1553-1561
A cDNA was cloned from the salivary glands of a blood-feeding black fl
y Simulium vittatum. The encoded protein has been given the name Simul
ium vittatum erythema protein or SVEP, because of its ability to incre
ase blood perfusion in skin capillaries, resulting in the well-charact
erized erythema of black fly bites. The full-length cDNA contains 548
base pairs which encode 152 amino acid residues of the nascent protein
. Post-translational processing produces a mature, secreted protein of
133 residues with a molecular mass of 15.4 kDa. Recombinant SVEP (rSV
EP) was produced in a baculovirus expression system and purified by a
one-step reversed-phase HPLC procedure. Analyses of physical propertie
s and biological potency demonstrated fidelity of rSVEP to the native
protein. Recombinant SVEP relaxed rabbit aorta preparations when preco
nstricted with 2 mu mol l(-1) phenylephrine or 25 mmol l(-1) K+ but no
t with 60 mmol l(-1) K+. Further, the rSVEP-induced relaxation respons
e of phenylephrine-constricted aorta was inhibited by glibenclamide (1
0 mu mol l(-1)), suggesting that at least part of its action to relax
smooth muscle may result from the opening of ATP-dependent K(+)channel
s. SVEP is a novel salivary-gland-derived vasoactive protein that may
be essential for blood feeding by black flies and could potentially en
hance transmissionof filarial parasites.