Cloning and characterization of vitellogenin gene of Indian malaria vector, Anopheles culicifacies, and comparison with other mosquito vitellogenin genes (Diptera: Culicidae)

The vitellogenin gene including 5’ upstream regulatory region of Anopheles culicifacies (AncuVg) was isolated, sequenced & characterized. The AncuVg sequence has been deposited in GenBank under accession number JN113091. It contained an ORF of approximately 6.2 KB encoding 2052 amino acids within a putative signal peptide of 16 residues. It also contains an N_Vitellogenin region and a VWF type D domain, that are found conserved in other insect Vgs too. The molecular weight of the predicted polypeptide was 238.0 kDa. It possesses four consensus (RXXR/S) cleavage sites and close to the C- terminus there is a GL/ICG motif followed by nine cysteine residues and a DGXR motif, located 18 residues upstream from the GL/ICCG motif. Three polyserine regions were found in the deduced amino acid sequence; two in the amino terminal region and one in the carboxy terminal region. The extent of codon bias in mosquito vitellogenin genes based on the relative synonymous codon usage values were determined by the effective number of codons. The 3D structure of Anopheles culicifacies Vg was also predicted. The 5’ upstream region of the AncuVg gene was analyzed to understand the regulation of Vg gene transcription. Phylogenetic analysis using the 5’ upstream region of Vg genes showed their conformation to three major clades among mosquitoes. Homology and other characteristic features of Vg have also been analyzed using various bioinformatic tools.