Carboxypeptidase B in Anopheles gambiae (Diptera: Culicidae) Effects of Abdominal Distention and Blood Ingestion

Abstract

Carboxypeptidase B (CPB) activity was detected in the guts of strain G-3 of Anopheles gambiae (Giles) and Aedes aegypti (L.). Mosquitoes were examined 3-5 d after emergence following exposure to 20% sucrose, from 0 to 4 h after feeding on a meal of latex beads in saline, and from 0 to 96 h after blood feeding. CPB activity was assayed in whole-gut homogenates, including lumenal contents and peritrophic matrix, by following the hydrolysis of a substrate specific for CPB-[3H]-benzoyl-L-Phe-L-Arg. Homogenates were divided into cytosolic plus lumenal components and membrane-associated components. Activity levels changed in response to feeding, decreasing in response to distention by saline plus latex and increasing only in response to blood. Overall, CPB activity was higher in unfed An. gambiae than in unfed Ae. aegypti. Detection of CPB activity in the peritrophic matrix of both species indicated that this enzyme was secreted actively into the gut lumen. In An. gambiae, CPB activity was optimal at pH 8, and thiol-type CPB was the predominant form detected. The data indicated that CPB in An. gambiae was regulated by both physical and chemical factors.

cpbAg1 encodes an active carboxypeptidase B expressed in the midgut of Anopheles gambiae

“…It has also been proposed that mosquito trypsin might activate Plasmodium chitinase and in doing so, help the parasite to cross the peritrophic matrix, a chitin‐rich structure that embeds the blood‐meal (Shahabuddin et al ., 1995) and constitutes a barrier that the parasite has to cross to pursue its development. Whereas Anopheles trypsins, chymotrypsins and aminopeptidases have been extensively studied (Billingsley & Hecker, 1991; Muller et al ., 1993a, b, 1995; Chadee & Beier, 1995; Chege et al ., 1996; Lemos et al ., 1996; Jahan et al ., 1999; Shen et al ., 2000; Vizioli et al ., 2001), only a few reports have examined Anopheles carboxypeptidases (Edwards et al ., 1997; Moskalyk, 1998; Jahan et al ., 1999).…”

“…In haematophagous insects, carboxypeptidase A activity is strongly up‐regulated upon blood feeding and genes encoding digestive carboxypeptidase A have been isolated from Simulium , Aedes and Anopheles (Ramos et al ., 1993; Edwards et al ., 1997, 2000; Noriega et al ., 2002). Midgut carboxypeptidase B activity has been reported in Glossina , Aedes and Anopheles (Gooding, 1977; Moskalyk, 1998; Noriega et al ., 2002) and a gene coding for carboxypeptidase B has been described in Glossina (Yan et al ., 2002). However, this gene most likely codes for a carboxypeptidase C with specificity towards glutamate residues (Bown & Gatehouse, 2004).…”

Molecular Characterization of the Carboxypeptidase B1 of Anopheles stephensi and Its Evaluation as a Target for Transmission-Blocking Vaccines

“…Furthermore, midgut activity of CPB has been reported in Glossina, Aedes, and Anopheles species (18,20,21). In addition, a gene that encodes CPB has been described in Glossina morsitans (22).…”

Structure of Aedes aegypti carboxypeptidase B1‐inhibitor complex uncover the disparity between mosquito and non‐mosquito insect carboxypeptidase inhibition mechanism

“…11 Although there are many MCP families, the M14 family is the largest, comprising four subfamilies: M14 A-type to M14 D-type. 11 In female mosquitoes, MCPs from the A-type (CPA) and B-type (CPB) subfamilies aid in the digestion of proteins found in ingested blood [12][13][14] ; this enzymatic activity is required to release essential amino acid residues for egg development and subsequently larval growth. 9,10,15,16 MCPs have also been implicated in facilitating malaria parasite infection within the mosquito midgut.…”