MOLECULAR-CLONING OF CDNAS FOR 2 PRO-PHENOL OXIDASE SUBUNITS FROM THEMALARIA VECTOR, ANOPHELES-GAMBIAE

Phenol oxidase exists in insect hemolymph as a zymogen, pro-phenol oxi dase (pro-PO), which is activated by specific proteolysis in response to infection or wounding, Phenol oxidase catalyses the synthesis of qu inones that polymerize to form melanin deposits, which encapsulate par asites and help to seal wounds, Antibodies to pro-PO from Manduca sext a bound to 76, 72, and 71 kDa polypeptide bands from hemolymph of Anop heles gambiae larvae, This antiserum was used to screen a cDNA library from A, gambiae fourth-instar larvae, Pub-length clones were isolated for two different pro-POs, designated A, gambiae proPO-p1 and proPO-p 2, which are 67% identical in nucleotide sequence and 66% identical in deduced amino acid sequence, The A, gambiae pro-PO sequences are more similar to pro-PO from Drosophila melanogaster than to lepidopteran o r crustacean pro-PO sequences in the GenBank database. Like the other arthropod pro-POs, the A, gambiae pro-PO sequences lack a signal pepti de and have two conserved regions predicted to bind two copper atoms i re the active site of the enzyme, The availability of these pro-PO cDN As should be useful in examining the biochemical differences between A , gambiae strains that are refractory or susceptible to Plasmodium inf ection, and differ in their ability to encapsulate the parasites, (C) 1997 Elsevier Science Ltd.