Groth Georg
Heinrich-Heine-Universität, Biochemie der Pflanzen, Universitätsstrasse 1, D-40225 Duesseldorf, Germany.
Proc Natl Acad Sci U S A. 2002 Mar 19;99(6):3464-8. doi: 10.1073/pnas.052546099.
Tentoxin, a natural cyclic tetrapeptide produced by phytopathogenic fungi from the Alternaria species affects the catalytic function of the chloroplast F(1)-ATPase in certain sensitive species of plants. In this study, we show that the uncompetitive inhibitor tentoxin binds to the alphabeta-interface of the chloroplast F(1)-ATPase in a cleft localized at betaAsp-83. Most of the binding site is located on the noncatalytic alpha-subunit. The crystal structure of the tentoxin-inhibited CF(1)-complex suggests that the inhibitor is hydrogen bonded to Asp-83 in the catalytic beta-subunit but forms hydrophobic contacts with residues Ile-63, Leu-65, Val-75, Tyr-237, Leu-238, and Met-274 in the adjacent alpha-subunit. Except for minor changes around the tentoxin-binding site, the structure of the chloroplast alpha(3)beta(3)-core complex is the same as that determined with the native chloroplast ATPase. Tentoxin seems to act by inhibiting inter-subunit contacts at the alphabeta-interface and by blocking the interconversion of binding sites in the catalytic mechanism.
细交链孢菌毒素是一种由链格孢属植物病原真菌产生的天然环状四肽，它会影响某些敏感植物物种中叶绿体F(1)-ATP酶的催化功能。在本研究中，我们发现非竞争性抑制剂细交链孢菌毒素结合在叶绿体F(1)-ATP酶的αβ界面上位于β-天冬氨酸-83处的一个裂隙中。大部分结合位点位于非催化性的α亚基上。细交链孢菌毒素抑制的CF(1)复合物的晶体结构表明，该抑制剂与催化性β亚基中的天冬氨酸-83形成氢键，但与相邻α亚基中的异亮氨酸-63、亮氨酸-65、缬氨酸-75、酪氨酸-237、亮氨酸-238和甲硫氨酸-274形成疏水接触。除了细交链孢菌毒素结合位点周围有微小变化外，叶绿体α(3)β(3)核心复合物的结构与天然叶绿体ATP酶所确定的结构相同。细交链孢菌毒素似乎是通过抑制αβ界面处的亚基间接触以及在催化机制中阻断结合位点的相互转化来发挥作用的。
