Thermal unfolding and modular architecture of Clostridium stercorarium Xyn10B.
To examine the possibility of module interaction in the thermal unfolding of different modular architectures, four truncated proteins were constructed from Clostridium stercorarium Xyn10B: a family 10 catalytic module (CM10), a polypeptide compound of one family 22 carbohydrate-binding module (CBM22-2) and the catalytic module (CBM22-CM10), two family 22 CBMs and the catalytic module (2CBM22-CM10), and only two family 22 CBMs (2CBM22). Thermal unfolding of four proteins were observed by differential scanning calorimetry. CM10 was unfolded reversibly and denatured as one component. The unfolding of protein CBM22-CM10 comprising CBM22-2 connected with CM10 was irreversible, and can be assumed to be one-component denaturation. Protein 2CBM22, with two CBM22s in tandem, unfolded as two independent modules. However, 2CBM22-CM10, with two CBM22s, unfolded as two and not the expected three separate components. These findings constitute the first reported case in which differences in thermal unfolding units and mechanisms were derived from differences in the modular architectures of proteins.
Araki
Rie
R
Sustainable Resource Sciences, Graduate School of Bioresources, Mie University, Tsu, Japan.
Karita
Shuichi
S
Tanaka
Akiyoshi
A
Suzuki
Miki
M
Kimura
Tetsuya
T
Sakka
Kazuo
K
D002152:Calorimetry, Differential Scanning; D050260:Carbohydrate Metabolism; D002384:Catalysis; D003013:Clostridium / Q000201:enzymology*; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D011489:Protein Denaturation; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D013696:Temperature; D013816:Thermodynamics
D011994:Recombinant Proteins; D043364:Endo-1,4-beta Xylanases