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.

Sequencing the Heat Inducible Hsp70 Gene

M.F.P. Heschl and D.L. Baillie

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.