Characterization of the cDNA encoding the 90 kDa heat-shock protein in theLepidoptera Bombyx mori and Spodoptera frugiperda

This report presents the first hsp90 complete cDNA sequences from two Lepid optera. The Bomb hr mori full sequence was reconstituted from 15 partial cD NA clones belonging to expressed sequence tag libraries obtained from diffe rent tissues or cultured cells, thus showing the ubiquitous expression of t he hsp90 gene. The Spodoptera frugiperda cDNA was isolated as a full-length clone from a cDNA library established from the Sf9 cell line. Both cDNAs a re highly homologous and display the classical amino acid (aa) stretches re presenting the HSP90 signature. They potentially encode a 716 as (B. mori) and a 717 as (S. frugiperda) protein, with a calculated molecular mass of 8 3 kDa similar to the Drosophila homologous protein. We show that, unlike th e vertebrates, hsp90 is a unique gene in both S. frupiperda and B. mori gen omes. Sequencing of the corresponding genomic region shows that, contrary t o the dipteran homologous gene, the lepidopteran hsp90 gene does not displa y any intron. Phylogenetic analysis based on the two lepidopteran and 23 ot her HSP90 as sequences displays a high consistency with known phylogeny at both high and low taxonomic levels. Transcriptional analysis performed in S . frugiperda shows that the induction of the hsp90 gene only occurs 14 degr eesC above physiological growth conditions (42 degreesC). (C) 2001 Publishe d by Elsevier Science B.V. All rights reserved.