Heat shock and developmental regulation of the Drosophila melanogaster hsp83 gene.

In contrast to the hsp70 gene, whose expression is normally at a very low level and increases by more than 2 orders of magnitude during heat shock, the hsp83 gene in Drosophila melanogaster is expressed at high levels during normal development and increases only severalfold in response to heat shock. Developmental expression of the hsp83 gene consists of a high level of tissue-general, basal expression and a very high level of expression in ovaries. We identified regions upstream of the hsp83 gene that were required for its developmental and heat shock-induced expression by assaying beta-galactosidase activity and mRNA levels in transgenic animals containing a series of 5' deletion and insertion mutations of an hsp83-lacZ fusion gene. Deletion of sequences upstream of the overlapping array of a previously defined heat shock consensus (HSC) sequence eliminated both forms of developmental expression of the hsp83 gene. As a result, the hsp83 gene with this deletion mutation was regulated like that of the hsp70 gene. Moreover, an in vivo polymer competition assay revealed that the overlapping HSC sequences of the hsp83 gene and the nonoverlapping HSC sequences of the hsp70 gene had similar affinities for the factor required for heat induction of the two heat shock genes. We discuss the functional similarity of hsp70 and hsp83 heat shock regulation in terms of a revised view of the heat shock-regulatory sequence.     

Nucleotide sequences of heat shock activated genes in Drosophila melanogaster. I. Sequences in the regions of the 5' and 3' ends of the hsp 70 gene in the hybrid plasmid 56H8.

We present the sequences at the 5' and 3' ends of one hsp 70 gene variant which is derived from the chromosomal locus 87A7. The 5' end of the hsp 70 mRNA has also been determined. 550 bp upstream from the 5' end of the hsp 70 mRNA, there is a very A+T rich region shown by heteroduplex analysis to be also present at the same position in other hsp 70 genes9. The 5' end of the hsp 70 mRNA was found 26 bp after a characteristic "Hogness box". The first ATG codon was found 250 bp downstream from the 5' end of the hsp 70 mRNA. We also determined the termination codon at the 3' end of the hsp 70 gene. Comparisons with other genes are discussed.     

Structure and expression of a rice hsp70 gene

A genomic hsp70 gene was isolated from a rice IR36 genomic library and 4 794 bp of the gene have been sequenoed. The 5' flanking region of the gene contained a putative TATA box and a typical heat shock element sequence 5'-CTcgGAAccTTCgAG-3'. The amino acid sequence of the rice HSP70 deduced from the coding region shared 84%-92% homologies with those of HSP70s from other plant species. An intron 1939bp long was identified in the coding region at the codon specifying amino acid 72 (Asp), the similar position introns occurring in other intron-containing hsp70 genes. In addition, another intron of 57 bp was found in the 3'-untranslated region in the rice hsp70 gene. Southern blot hybridization showed that rice hsp70 gene family contained at least three members. Analysis of the RNA leveis with the gene-specific and non-specific probes revealed that the rice hsp70 gene expressed at normal temperature and the expression was enhanced by heat shock treatment.     

The structure and expression of maize genes encoding the major heat shock protein, hsp70

We have isolated and sequenced two maize genomic clones that are homologous to the Drosophila hsp70 gene. One of the maize hsp70 clones contains the entire hsp70 coding region and 81 nucleotides of the 5' nontranslated sequence. The predicted amino acid sequence for this maize protein is 68% homologous to the hsp70 of Drosophila. The second maize hsp70 clone contains only part of the coding sequence and 1.1 kb of the 5' flanking sequence. This 5' flanking sequence contains two sequences homologous to the consensus heat-shock-element sequence. Both maize genes are thermally inducible and each contains an intron in the same position as that of the heat-shock-cognate gene, hsc1, of Drosophila. The presence of an intron in the maize genes is a distinguishing feature in that no other thermally inducible hsp70 genes described to date contain an intron. We have constructed a hybrid hsp70 gene containing the entire hsp70 coding sequence with an intron, and 1.1 kb of the 5' flanking sequence. We demonstrate that this hybrid gene is thermally inducible in a transgenic petunia plant and that the gene is expressed from its own promoter.