Highly conserved charge-pair networks in the mitochondrial carrier family
Highly conserved charge-pair networks in the mitochondrial carrier family
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DOI：
10.1006/jmbi.1997.1594
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发表时间：
1998-03-27
影响因子：
5.6
通讯作者：
Swanson, JM
中科院分区：
文献类型：
--
作者：
Nelson, DR;Felix, CM;Swanson, JM
对酵母 ADP/ATP 载体 AAC2 中功能恢复突变的选择揭示了一系列意想不到的电荷对。所涉及的六个氨基酸中的四个存在于用于定义该蛋白质家族的线粒体能量转移基序中。因此，ADP/ATP 载体的结果可能适用于整个家庭。线粒体载体由三个同源结构域构建，每个结构域均具有保守基序 PX(D,E)XX(K,R)。中和这些基序中 K48、R152 或 R252 处的保守正电荷会导致酵母呼吸缺陷。 D149和D249处的负电荷的中和也使得呼吸缺陷酵母，通过E45G或E45Q突变体能够在甘油上生长。当分子中另一个位点失去互补电荷时，功能就会恢复。这种现象已被独立观察到八次，因此是受影响残基之间存在电荷对的有力证据。通过这种方法在酵母 AAC2 中检测到了五个不同的电荷对，并且可以根据结构域之间的同源性预测另外三个。三个线粒体能量转移特征之内或之间发生的高度保守的电荷对似乎是线粒体载体结构的关键特征，与运输的底物无关。替代电荷对之间的构象转换可能构成运输基础的一部分。 (C) 1998 学术出版社有限公司。
Selection for regain-of-function mutations in the yeast ADP/ATP carrier AAC2 has revealed an unexpected series of charge-pairs. Four of the six amino acids involved are found in the mitochondrial energy transfer motifs used to define this family of proteins. As such, the results found with the ADP/ATP carrier may apply to the family as a whole. Mitochondrial carriers are built from three homologous domains, each with the conserved motif PX(D,E)XX(K,R). Neutralization of the conserved positive charges at K48, R152 or R252 in these motifs results in respiration defective yeast. Neutralization of the negative charges at D149 and D249 also make respiration defective yeast, through E45G or E45Q mutants are able to grow on glycerol. Regain of function occurs when a complementary charge is lost from another site in the molecule. This phenomenon has been observed independently eight times and thus is strong evidence for charge-pairs existing between the affected residues. Five different charge-pairs have been detected in the yeast AAC2 by this method and three more can be predicted based on homology between the domains. The highly conserved charge-pairs occurring within or between the three mitochondrial energy transfer signatures seem to be a critical feature of mitochondrial carrier structure, independent of the substrates transported. Conformational switching between alternative charge-pairs may constitute part of the basis for transport. (C) 1998 Academic Press Limited.