Redox-dependent Changes in Structure and Function of
hHSF1
LIN Zheng*, HUANG Fan, MA Zhong-Fu, XU
Kang, LIU Alice Y1
( The
First Hospital Affiliated to Sun Yat-Sen University, Guangzhou, 510080 China; 1Department
of Cell Biology and Neuroscience, Rutgers State University of New Jersey 08854,
USA )
Abstract To
evaluate the effects of cysteine-SH-directed regents on the redox status,
structure and function of human heat shock transcription factor 1 (hHSF1),
treatment in vitro of hHSF1 with 0.3–0.5 mmol/L oxidizing reagent diamide (DM) and
treatment in vivo of HeLa cells with 1 mmol/L buthionine sulfoximine (BSO), an
inhibitor of g-glutamylcysteine synthetase, promoted the formation of a compact,
intramolecularly disulfide-crosslinked, stable monomeric form of ox-hHSF1, and
blocked the trimerization and activation of HSF1. The effects of diamine were
dose-dependent and readily could be completely reversed by adding 0.4–0.5 mmol/L
reducing reagent dithiothreitol (DTT) to the samples prior to gel
electrophoresis. Computer modeling of the a-helical coiled-coil
domains of the HSF1 monomer and trimer showed that the alignment of the N- and
C-terminal hydrophobic repeats of HSF1 monomer could bring C3 (Cys153) close to
C4 and C5 (Cys373 and Cys378, respectively), in positions permissible for
disulfide bond formation under appropriate experimental conditions. The results
suggest that redox-dependent thiol-disulfide exchange can provide a mechanism
for regulation the conformation and activity of hHSF1.
Key words hHSF1;
redox; thiol; cysteine
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author: Tel, 86-20-87331142; e-mail,
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