CLONING AND SEQUENCE-ANALYSIS OF CDNA-ENCODING A PUTATIVE JUVENILE-HORMONE ESTERASE FROM THE COLORADO POTATO BEETLE

In the Colorado potato beetle, Leptinotarsa decemlineata, reproduction and diapause are mediated by the juvenile hormone (JH) titer in the h emolymph, This titer is controlled by JH synthesis in the corpora alla ta and by JH degradation, The main pathway of JH degradation is by JH esterase in the hemolymph, The native JH esterase appeared to be a dim er consisting of two 57 kDa subunits (Vermunt et al., 1997), The 57 kD a subunit of JH esterase was digested with endoproteinase Lys-C and th e digestion products were separated by reversed phase HPLC. Three diff erent peptides were collected and sequenced, The amino acid sequence o f one peptide showed high similarity to fragments of other insect este rases, Based on the amino acid sequence of these peptides, degenerate primers were constructed for RT-PCR, A PCR product of 1.3 kb was obtai ned and sequenced, This product was used to screen a cDNA library for a complete cDNA copy and to analyze the messenger RNA from larvae and adult beetles, The size of the messenger RNA was 1.7 kb, The complete amino acid sequence of the protein was deduced from the nucleotide seq uence of overlapping clones from a cDNA library and a 5'RACE product, An open reading frame (ORF) of 1545 base pairs encoded a 57 kDa protei n with a predicted pi of 5.5, The ORF contained the sequences of the t hree peptides, It showed no significant homology to other proteins pre sent in databases, but it did contain several functional esterase moti fs, (C) 1998 Elsevier Science Ltd, All rights reserved.