Redox-regulated chaperone function and conformational changes of Escherichia coli Hsp33.
We have studied the chaperone activity and conformation of Escherichia coli heat shock protein (Hsp)33, whose activity is known to be switched on by oxidative conditions. While oxidized Hsp33 completely prevents the heat-induced aggregation of zeta-crystallin at 42 degrees C at a ratio of 1:1 (w/w), the reduced form exhibits only a marginal effect on the aggregation. Far UV-circular dichroism (CD) spectra show that reduced Hsp33 contains a significant alpha-helical component. Oxidation results in significant changes in the far UV-CD spectrum. Near UV-CD spectra show changes in tertiary structural packing upon oxidation. Polarity-sensitive fluorescent probes report enhanced hydrophobic surfaces in the oxidized Hsp33. Our studies show that the oxidative activation of the chaperone function of Hsp33 involves observable conformational changes accompanying increased exposure of hydrophobic pockets.
Centre for Cellular and Molecular Biology, 500 007, Hyderabad, India.
B
B
Raman
L V
LV
Siva Kumar
T
T
Ramakrishna
C
C
Mohan Rao
D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D002942:Circular Dichroism; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000737:chemistry* / Q000235:genetics; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018832:Molecular Chaperones / Q000378:metabolism / Q000502:physiology; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D011487:Protein Conformation
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C492165:HSP33 protein, E coli; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones