[1P-2] ポスター1（1P-49ー1P-87）

[1P-60*] 異種由来のサブユニットから成るハイブリッドF1-ATPaseの回転特性

^○渡邉 亮¹, ザルコ－ザバラ マリエル¹, タス ブスラ², 小林 稜平¹, 上野 博史¹, リ チュン－ビュー², 野地 博行¹ (1.東大・院・工, 2.ストックホルム大)

F₁-ATPase(F₁) is a rotary molecular motor. The minimum complex of F₁ required for rotation is α₃β₃γ₁, in which the γ subunit is inserted in the central cavity of the α₃β₃-ring. During ATP hydrolysis, structural change of catalytic subunit β causes rotation of γ. Extensive rotation assays have revealed the variation in rotary properties among F₁s from thermophilic Bacillus PS3, bovine mitochondria and Paracoccus denitrificans, despite the close sequence homology. An arising question is, what is the dominant factor for the variation? Here, to identify the dominant subunit, we constructed 8 types of hybrid F₁s consisting of subunits from the three genuine F₁s and compared the rotary properties: rotational rate and stepping size in rotation. Rotation assays of the hybrid F₁s revealed strong correlation between rotational rate and the species from which the α and β subunits are derived. We have succeeded in constructing a mathematical model that describes the correlation. It suggests the dominance of both of α and β over rotational rate. However, strong correlation between stepping size and each subunit was not found. These results suggest that the rotary properties of F₁ are determined by combination of subunits, but not a particular subunit.