Purification and characterization of the 16-kDa heat-shock-responsive protein from the thermophilic cyanobacterium Synechococcus vulcanus, which is an alpha-crystallin-related, small heat shock protein.
A 16-kDa protein, one of the major proteins that accumulates upon heat-shock treatment in the thermophilic cyanobacterium Synechococcus vulcanus, was purified to apparent homogeneity. The N-terminal and internal amino acid sequences of the protein exhibited a homology to the alpha-crystallin-related, small heat shock proteins from other organisms. The protein was designated HspA. Size-exclusion chromatography and nondenaturing gel electrophoresis demonstrated that HspA formed a large homo-oligomer consisting of 24 subunits. It prevented the aggregation of porcine malic dehydrogenase at 45 degrees C and 50 degrees C and citrate synthase at 50 degrees C. The activity of the malic dehydrogenase, however, was not protected under these heat-shock conditions or reactivated after a shift in temperature from 45 or 50 degrees C to 21 degrees C. HspA was able to enhance the refolding of chemically denatured rabbit muscle lactate dehydrogenase in an ATP-independent manner. A homologue to the 16-kDa protein was also found to be induced upon heat-shock treatment in the mesophilic cyanobacterium Synechocystis sp. PCC 6803.
Roy
S K
SK
Department of Biochemistry, Saitama University, Urawa, Japan.
Hiyama
T
T
Nakamoto
H
H
D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins; D001704:Biopolymers; D015153:Blotting, Western; D002851:Chromatography, High Pressure Liquid; D003459:Crystallins / Q000737:chemistry*; D000458:Cyanobacteria / Q000737:chemistry*; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*; D018869:Heat-Shock Response; D008291:Malate Dehydrogenase / Q000037:antagonists & inhibitors; D008969:Molecular Sequence Data; D011817:Rabbits; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D017386:Sequence Homology, Amino Acid
D001426:Bacterial Proteins; D001704:Biopolymers; D003459:Crystallins; D006360:Heat-Shock Proteins; C113725:HspA protein, bacteria; D011994:Recombinant Proteins; D008291:Malate Dehydrogenase