Worm Breeder's Gazette 9(1): 15
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
Three genes showing homology to a Drosophila melanogaster hsp70 gene have been previously isolated [Snutch and Baillie, MGG 195, 329 (1984) ]. One of these three genes, the class A gene,is heat inducible and has been suggested to be the major heat inducible hsp70 gene in C. elegans. We have started to sequence the 5' flanking regions and the 5' coding region of the class A gene which is carried in the plasmid pUC19 (Nevins, pers. comm.). We have generated several exonuclease III deletions [Henikoff, Gene 28, 351 (1984)] to facilitate the sequencing. Several interesting observations have been made. 1) There are four Pelham consensus sequences (a 14 nucleotide sequence with dyad symmetry important for heat shock inducibility [Pelham, Cell 30, 517 (1982)]). One at approximately -280 with respect to the presumptive start of transcription (about 30 bp downstream of the TATA box) and one at approximately +4 show 70% homology. Sequences at -65 and one within the coding region show 90% homology with the consensus sequence. 2) The amino acid sequence, as deduced from the nucleotide sequence, shares a 75% homology with both D. melanogaster and human hsp70 amino acid sequences [Ignolia et al., Cell 21, 669 (1980); Voellmy et al., PNAS 82, 4948 (1985)]. 3) The presence of an intron of 46 bp has been detected at least 92 amino acids into the coding region (the start of translation has not been sequenced yet). The intron was detected by a sharp drop in amino acid homology with the human sequence only to have the homology continue further on down the sequence in a different reading frame. It was also evident when a homology matrix was done against the human hsp70 nucleotide sequence. 4) The intron shares several features with the introns from the hsp16 genes [Russnack and Candido, MCB 5, 1268 (1985)]. The sequence TTTTCAA is found 15 bp into the intron of the hsp70 gene and 17 bp into the introns of the 16-1 and 16-48 hsp genes. This sequence shares homology with the lariat consensus sequence for removal of introns [Bangeford et al., Cell 36, 645 (1984)]. At the 3' intron boundary, the sequence TTTCAG (as reported by Blumenthal et al., C. elegans newsletter 8,1) is conserved in all three introns. At the 5' boundary, the hsp70 and 16 genes share a 60% homology with the 5' consensus sequence described by Blumenthal et al. (GTRAGTTTTT; 70: GTGctTaaTT; 16-1: GTAAGTaaca; 16-48: GTAAGaaaaT). The presence of this intron is interesting in that this is the first heat inducible hsp70 gene to be described which contains an intron This suggests that the class A gene may not be the major heat inducible hsp70 gene in C. elegans or, alternatively, the intron may be used for some form of post-transcriptional control.