NUCLEOTIDE AND DEDUCED AMINO-ACID-SEQUENCE OF A CDNA CLONE ENCODING DIAPAUSE PROTEIN-1, AN ARYLPHORIN-TYPE STORAGE HEXAMER OF THE COLORADO POTATO BEETLE

Several clones encoding diapause protein 1 have been isolated by immunoscreening a cDNA library, constructed from poly(A)RNA of whole Colorado potato beetles reared under short-day conditions. The clones contained overlapping DNA sequences, but none contained the complete sequence of the protein. The nucleotide and deduced amino acid sequence of the longest clone (Dp19) is presented. This clone encodes 670 amino acids; the first five were similar to the last five of the 20 N-terminal amino acids determined by protein sequencing. Thus, the subunit of diapause protein 1 is composed of 685 amino acids with a predicted molecular weight of 81,317. The deduced amino acid composition revealed that the proportion of tyrosine/phenylalanine is 16.6%, which suggests that the protein is an arylphorin-type storage hexamer. Hybridization experiments with total RNA and poly(A)RNA from larvae and adults revealed that the gene is expressed in last instar larvae and in adults reared under short-day conditions but not in third-instar larvae and long-day adults. Topical application of pyriproxyfen suppresses the transcription of the messenger. This suggests that the gene for diapause protein 1 is transcribed only under conditions of low juvenile hormone titres. Southern blot experiments showed that the gene for diapause protein 1 occurs only once in the haploid genome of the Colorado potato beetle.