Fusion surface structure, function, and dynamics of gamete fusogen HAP2
Fusion surface structure, function, and dynamics of gamete fusogen HAP2
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DOI：
10.7554/elife.39772
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发表时间：
2018-10-03
期刊：
影响因子：
7.7
通讯作者：
Springer, Timothy A.
中科院分区：
文献类型：
--
作者：
Feng, Juan;Dong, Xianchi;Springer, Timothy A.
HAP 2是许多真核生物界中的II类配子融合子。衣原体HAP 2的晶体结构显示三聚体融合状态。结构域D1、D2.1和D2.2排列在3重轴上; D3和茎包抵靠外表面。令人惊讶的是，氢-氘交换表明，最接近3重轴的D1、D2.2和D3的表面比暴露的表面更动态。每个单体的融合环中的三个融合螺旋在三聚体顶点处暴露疏水性残基，所述疏水性残基从3倍轴张开，在每个单体中的融合环之间留下溶剂填充的空腔。在两个融合环的底部，Arg 185停靠在羰基笼中。与其他结构，动力学，和更大的影响衣原体配子融合的突变轴近端比轴远端融合螺旋的比较表明，每个单体的顶端部分可以向3倍轴倾斜合并的融合螺旋成一个共同的融合表面。
HAP2 is a class II gamete fusogen in many eukaryotic kingdoms. A crystal structure of Chlamydomonas HAP2 shows a trimeric fusion state. Domains D1, D2.1 and D2.2 line the 3-fold axis; D3 and a stem pack against the outer surface. Surprisingly, hydrogen-deuterium exchange shows that surfaces of D1, D2.2 and D3 closest to the 3-fold axis are more dynamic than exposed surfaces. Three fusion helices in the fusion loops of each monomer expose hydrophobic residues at the trimer apex that are splayed from the 3-fold axis, leaving a solvent-filled cavity between the fusion loops in each monomer. At the base of the two fusion loops, Arg185 docks in a carbonyl cage. Comparisons to other structures, dynamics, and the greater effect on Chlamydomonas gamete fusion of mutation of axis-proximal than axis-distal fusion helices suggest that the apical portion of each monomer could tilt toward the 3-fold axis with merger of the fusion helices into a common fusion surface.