K. Unno et al., ROLE OF HSP70 SUBFAMILY, SSA, IN PROTEIN-FOLDING IN YEAST-CELLS, SEENIN LUCIFERASE-TRANSFORMED SSA MUTANTS, Biological & pharmaceutical bulletin, 20(12), 1997, pp. 1240-1244
To investigate the role of constitutive hsp70 in protein folding and t
o probe tile supplementation by other hsps in this folding, yeast tell
s espressing reduced constitutive hsp70 proteins, ssa1ssa2, were trans
formed with a plasmid espressing a bacterial luciferase protein. With
several independent clone cells of transformants, the levels of lucife
rase activity and some hsps, such as hsp104, hsp90, hsp70 and hsp26, w
ere examined, The luciferase activity mas significantly lower in ssa1s
sa2 transformants than in the wild type (wt) cell transformed with the
same plasmid. Among several clone cells of ssa1ssa2, the cells with h
igher luciferase activities exhibited higher amounts of Ssa4 which is
known to be expressed instead a lacking Ssa1 and Ssa2. The luciferase
activity closely correlated with the amount of Ssa proteins, mere than
with the amount of other hsps, It is suggested that constitutional Ss
a ''chaperones'' are needed for the folding of proteins and, in cells
lacking Ssa1 and Ssa2 the increased Ssa4 is thought to partly compensa
te for their role irt the folding of luciferase in vivo.