Worm Breeder's Gazette 9(3): 72

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.

Update on a Heat Inducible Hsp70 Gene

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

The hsp70A gene (referred to previously as the hsp70 class A gene) 
is both a heat inducible and a developmentally expressed hsp70 gene.  
Sequencing of the hsp70A gene has been completed in an effort to 
determine the similarities to a Drosophila heat inducible hsp70 gene (
Ingolia, et. al., Cell 21, 669 (1980)) and to a developmentally 
expressed, or cognate, hsp70 gene (hsc4; M. Slater and E.A. Craig, 
pers. commun.) which is also induced upon heat shock.
We have found:  (1)  At the 5' region of the hsp70A gene, there are 
three heat shock elements (HSE; Pelham, Cell 30, 517 (1982)).  (2)  
Within the transcribed region, there are a total of three introns (IS1,
49 bp; IS2 194 bp; IS3, 55 bp).  (3)  At the 3' end of the gene, 
there appears to be a second, overlapping gene which has transcription 
and translation starts before the polyA addition site for the hsp70A 
gene.  (4)  The hsp70A amino acid sequence exhibits more homology with 
the hsc4 protein (79%) than with the heat inducible protein (71%).  (5)
There is more homology of the carboxy terminus of the hsp70A amino 
acid sequence with the hsc4 amino acid sequence than with the heat 
inducible hsp70 amino acid sequence.  The carboxy terminus appears to 
'define' the type of function for each hsp70 gene.
The hsp70A gene is expressed at high levels during development and 
its expression is increased two to six fold higher upon heat shock.  
The hsp70A mRNA appears to be the major hsp70 mRNA during both 
development and heat shock (T. Snutch, Ph.D. Thesis, Simon Fraser 
University, 1984).  The hsc4 gene is also expressed at high levels 
during development and its expression is increased two fold upon 
heat shock.  It is also the major hsp70 mRNA during development and 
during heat shock (Palter, et. al., MCB 6, 1187 (1986)).
Based upon the amino acid homologies and the similarities in 
expression, we believe that the hsp70A gene is analogous to the hsc4 
gene from Drosophila.  We predict that mutations of the hsp70A gene 
will be one of two types.  The first could be lethal due to the lack 
of an essential hsp70 protein.  The second could be 'temperature 
sensitive'.  That is, a mutation with no effects at low temperatures 
because the function of the hsp70A gene would be compensated for by 
other genes but lethal at higher temperatures when the hsp70A gene 
function cannot be compensated for.  The hsp70A gene has been mapped 
to the right arm of LGIV approximately 0.1 mu to the left of dpy-4 (
Snutch, et. al., submitted) using RFLDs.  A search for mutations in 
this area will be done to define alleles of hsp70A.