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application/pdf, Type I chaperonins (Cpn60/Hsp60) are essential proteins that mediate the correct folding of newly translated and stress-denatured proteins in bacteria, chloroplast and mitochondria. Despite the high sequence homology among chaperonins, there are some critical differences at the mechanistic level between the bacterial and the mitochondrial chaperonins with respect to their oligomeric state and their ability to function with co-chaperonins from different sources. Asp52 and Asp398 in Escherichia coli chaperonin GroEL are known as the critical residues on ATP hydrolysis because GroELD52A/D398A mutant is severely deficient in ATP hydrolysis but not in ATP binding. Here, yeast mitochondria Hsp60 (mHsp60) and Thermus thermophilus Hsp60 (TCpn60) were used to investigate the functional commonality of these two well-conserved Asp in ATP hydrolysis. These residues in GroEL correspond to Asp73 and Asp420 in mHsp60 and to Asp51 and Asp396 in TCpn60, respectively. We found that ATPase activity of mHsp60D73A and mHsp60D420A mutants were ~20% and < 4% of wild type, respectively, indicating that functional commonality of two Asp was shown in yeast mHsp60, despite suggesting different roles of Asp51 in TCpn60, surprisingly.

application/pdf, 神奈川工科大学 学位論文 令和3年3月20日授与(甲第43号)

application/pdf, Chaperonin GroEL is double ring structure which constructed with 14-mer of 57 kDa subunits. GroEL has two cavities to trap both newly polypeptides and denatured proteins, and folds them with co-chaperonin GroES and ATP. Both Asp-52 and Asp-398 in E. coli GroEL are important for ATP hydrolysis. The ATPase activity of GroEL(D52A/D398A) mutants was

application/pdf, The chaperonin GroEL is a double-ring structure which is constructed with 7 subunit ring of 57 kD, and those ring forms back to back. GroEL is bound with ATP and the co chaperon GroES for assisting protein folding in the cell. GroES is a septemer ring structure of 10 kD, and forms an asymmetric bullet shaped complex and a symmetric football shaped complex with GroEL. We tried to encapsulate metal nano particle in the mutant GroEL which can constructs stable football shaped complexes. High efficiency encapsulation of FePt nano particles in the mutant GroEL complexes was shown by TEM observation.

application/pdf, Aqueous uranyl acetate has been extensively used as a supeb staining reagent for transmission electron microscopy of biological materials. However, recent regulation of nuclear fuel material severely restricts its use. Since uranyl acetate is hazardous due to biological toxicity and remaining radioactivity, we examined gadolinium acetate (GdAc), a novel staining reagent for negative-staining electron microscopy in comparison with phosphotungstic acid (PTA). As a result, fine TEM images were observed when bacterial cells of Escherichia coli and Thermus thermophilus were respectively stained with I % PTA and 2.5 % GdAc. When GroEL/GroES complexes were stained, the high density sample on the grid was buried in the I % PTA, unless dilution of PTA or GroEUGroES complexes. On the other hand, 2.5 % GdAc stainning made it possible to observe high density sample clearly without dilution. We revealed that Gc!Ac reagents possess excellent capability for staining of bacterial cells (～μm) and GroEL/GroES complexes (～10 nm). GdAc can also be utilized as good negative-staining reagent to study supramolecular architecture ofbiologicall materials.