Crystal structures of MS2 capsids with mutations in the subunit FG loop.
Crystal structures of MS2 capsids with mutations in the subunit FG loop.
复制标题
亚基 FG 环发生突变的 MS2 衣壳的晶体结构。
DOI：
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发表时间：
1996
影响因子：
5.6
通讯作者：
L. Liljas
中科院分区：
文献类型：
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作者：
N. Stonehouse;K. Valegård;K. Valegård;R. Golmohammadi;R. Golmohammadi;S. Worm;S. Worm;Catherine Walton;Catherine Walton;Peter G. Stockley;Peter G. Stockley;L. Liljas;L. Liljas
噬菌体MS2外壳蛋白亚基的F和G β链之间的环（FG环）围绕T=3蛋白壳的5倍和3倍（准6倍）轴形成亚基间接触。在衣壳中，环以两种非常不同的构象存在，一种在形成5倍接触的B亚基中，另一种在形成准6倍接触的A和C亚基中。一个脯氨酸残基，Pro 78，在所有相关噬菌体的外壳蛋白中是严格保守的，并且在MS 2的情况下，该脯氨酸残基之前是B亚基中的顺式肽键。为了探测FG环在衣壳组装中的作用，我们已经确定了两个MS2衣壳的晶体结构，所述两个MS2衣壳由在FG环中的两个位置P78N或E76D具有突变的外壳蛋白形成。这些突变体显示FG环的构象变化，这解释了衣壳的温度稳定性降低。P78N突变体在第78位具有正常的反式肽键。
The loop between the F and G beta strands (FG loop) of the bacteriophage MS2 coat protein subunit forms inter-subunit contacts around the 5-fold and 3-fold (quasi 6-fold) axes of the T=3 protein shell. In capsids, the loop is found in two very different conformations, one in B subunits, which form the 5-fold contact, and one in A and C subunits, which form the quasi 6-fold contact. One proline residue, Pro78, is strictly conserved in the coat protein of all related bacteriophages, and in the case of MS2 this proline residue is preceded by a cis peptide bond in the B subunit. In order to probe the role of the FG loop in capsid assembly, we have determined the crystal structures of two MS2 capsids, formed by coat proteins with mutations at two positions in the FG loop, P78N or E76D. These mutants show conformational changes in the FG loops that explain the reduced temperature stability of the capsids. The P78N mutant has a normal trans peptide bond at position 78.