Characterization and phylogenetic analysis of carboxypeptidase A gene of Indian malaria vector, Anopheles culicifacies (Diptera: Culicidae)

Carboxypeptidases are hydrolases that cleave one amino acid residue at a time from carboxyl terminus of the protein. The expression of Carboxypepidase A (CPA) is rapidly induced by blood meal which makes the regulatory regions of CPA important to drive the expression of anti-parasitic gene. This in turn should help draw strategies for malaria control through vector transgenesis. The Carboxypeptidase A (CPA) of Indian malaria vector Anopheles culicifacies was cloned. The CPA gene has an Open Reading Frame of 1290 base pairs which encodes a putative protein of 429 amino acids. Insilico 3D structure of putative protein predicted the signature of zinc peptidase with GLN at 186, GLU at 186, HIS` at 308 and Ser amino acids at position 309 as the catalytic residues in the active centre of the enzyme. The analysis of 550 bp upstream sequence of CPA revealed the putative regulatory motifs i.e. the transcription start site and TATA box. A marker consensus of arthropod genes the ‘arthropod initiator sequence’ was also located in the core promoter region of the gene. The putative binding sites for transcription binding factors of insect were also revealed. BLAST searches of the gene in NCBI database shared homology with carboxypeptidase gene from mosquitoes and other blood feeding insects. The organization of CPA gene was also studied in available mosquito genomes. Phylogenetic analysis of CPA with available carboxypeptidase sequences within class insecta showed that the gene is evolutionary most close to Anopheles gambiae. The overall topology of the phylogenetic tree also indicated that the gene is closely related in blood feeding insects.