hsp80 of Neurospora crassa: cDNA cloning, gene mapping, and studies of mRNA accumulation under stress.

Using mRNA isolated from Neurospora crassa mycelium, grown for 14 h at normal growth temperature of 28 degrees C, and heat shocked for 1 h at 48 degrees C, a cDNA library was prepared in the expression vector lambda gt11. Following immunoscreening of this library with a polyclonal antiserum raised against a 80-kilodalton heat-shock protein (HSP80), cDNA clones containing 1.1- and 1.4-kilobase inserts were selected. Analysis of the partial nucleotide sequence and the deduced amino acid sequence of the cDNA clones revealed a remarkable extent of homology with other eukaryotic stress-90 family proteins; 85% identity of the amino acid sequence with that of yeast HSP90(82) was seen. The C-terminal end of the sequence contained the MEEVD motif, characteristic of eukaryotic stress proteins with a predominantly cytosolic localization. The gene for N. crassa HSP80 was mapped to the right arm of linkage group V, using restriction fragment length polymorphism mapping. Its expression during heat shock and recovery was monitored by probing Northern blots of RNA isolated from mycelium grown under various stress conditions.