Stabilization due to dimer formation of phosphoribosyl anthranilate isomerase from Thermus thermophilus HB8: X-ray Analysis and DSC experiments.
The crystal structure of phosphoribosyl anthranilate isomerase (PRAI) from Thermus thermophilus HB8 (TtPRAI) was solved at 2.0 A resolution. The overall structure of TtPRAI with a dimeric structure was quite similar to that of PRAI from Thermotoga maritima (TmPRAI). In order to elucidate the stabilization mechanism of TtPRAI, its physicochemical properties were examined using DSC, CD, and analytical centrifugation at various pHs in relation to the association-dissociation of the subunits. Based on the experimental results for TtPRAI and the structural information on TtPRAI and TmPRAI, we found that: (i) the denaturation of TtPRAI at acidic pH is correlated with the dissociation of its dimeric form; (ii) the hydrophobic interaction of TtPRAI in the monomer structure is slightly greater than that of TmPRAI, but dimer interface of the TmPRAI is remarkably greater; (iii) the contributions of hydrogen bonds and ion bonds to the stability are similar to each other; and (iv) destabilization due to the presence of cavities in TtPRAI is greater than that of TmPRAI in both the monomer and dimer structures.
Taka
Junichiro
J
RIKEN Harima Institute at SPring8, 1-1-1 Kohto, Mikazukicho, Sayo, Hyogo 679-5148.
Ogasahara
Kyoko
K
Jeyakanthan
Jeyaraman
J
Kunishima
Naoki
N
Kuroishi
Chizu
C
Sugahara
Mitsuaki
M
Yokoyama
Shigeyuki
S
Yutani
Katsuhide
K
D019747:Aldose-Ketose Isomerases / Q000737:chemistry*; D000595:Amino Acid Sequence; D001665:Binding Sites; D002152:Calorimetry, Differential Scanning; D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D019281:Dimerization; D004795:Enzyme Stability; D004926:Escherichia coli / Q000201:enzymology; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020836:Protein Structure, Quaternary; D016415:Sequence Alignment; D013824:Thermus / Q000201:enzymology; D016963:Thermus thermophilus / Q000201:enzymology*
D019747:Aldose-Ketose Isomerases; C029865:phosphoribosylanthranilate isomerase