Open AccessHeat shock inhibits and activates different protein degradation pathways and proteinase activities in Neurospora crassa
Author(s) -
Mohsenzadeh Saadat,
Xu Cunshuan,
Fracella Franco,
Rensing Ludger
Publication year - 1994
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1994.tb07287.x
Subject(s) - neurospora crassa , heat shock protein , cycloheximide , hsp70 , biochemistry , shock (circulatory) , heat shock , gel electrophoresis , protein degradation , polyacrylamide gel electrophoresis , biology , chemistry , microbiology and biotechnology , protein biosynthesis , enzyme , mutant , medicine , gene
In Neurospora crassa , heat shock treatment inhibits proteolytic activity. ATP‐independent proteinases were analysed after polyacrylamide gel electrophoresis using renaturing gelatine gels. Proteinases of 24, 29, and 130 kDa were shown to be inhibited by heat shock and were further characterized as to their properties. A major part of the heat shock‐induced inhibition is probably due to suppression of de novo synthesis of proteinases as deduced from experiments with cycloheximide. During several hours of recovery from heat shock, the inhibition of overall protein degradation and ATP‐independent proteinases is reversed. Azocasein assays as well as pulse‐chase experiments further showed that ATP‐dependent protein degradation is only slightly affected by heat shock. Two ATP‐binding proteinases of about 60 and 160 kDa even show an increased activity after heat shock. The degradation rate of heat shock proteins is inhibited by heat shock treatment, indicating that they are degraded by ATP‐independent proteinases. Western blot analysis of a ∼40‐kDa degradation product of HSP70 containing its amino terminal portion revealed a reduction in the amount of this peptide after heat shock.