Cloning and characterization of Aedes aegypti blood downregulated chymotrypsin II

Abstract

Aedes aegypti adult and larval blood downregulated chymotrypsin II was cloned, sequenced and its 3D conformation modeled. Cloning of the enzymes from adult and larval guts indicated that both genes sit at the same location on Chromosome 2. Genomic analyses showed that larval and adult genes are the same and both have four exons and three introns that are located on an 8.32 Kb DNA in direction with the Ae. aegypti genome. The adult and larval transcript synthesis is controlled by alternative splicing explaining small difference in the amino acids sequences. Chymotrypsin II that was extracted from guts of sugar‐fed and at 48 after blood feeding showed a pH optimum of 4–5 with a broad shoulder of activity from pH 6 to 10. Dot blot analyses show that the enzyme's transcript is downregulated after females take a blood meal and upregulated at 48 h after the blood meal. A Chymotrypsin II transcript was also detected in the larval gut during different times of larval developmental stages, indication that Ae. aegypti chymotrypsin II is synthesized by adults and larval guts. The possibility that JH III and 20HE play an active role in the regulation is discussed.