Kayne P S, Kim U J, Han M, Mullen J R, Yoshizaki F, Grunstein M
Molecular Biology Institute, University of California, Los Angeles 90024.
Cell. 1988 Oct 7;55(1):27-39. doi: 10.1016/0092-8674(88)90006-2.
Yeast histone H4 function was probed in vivo by deleting segments of this extremely conserved 102 amino acid protein. Deletions in the hydrophobic core of H4 are lethal and block chromosomal segregation. In contrast, deletions at the hydrophilic N terminus (residues 4-28) and C terminus (residues 100-102) are viable. However, N-terminal deletion alters normal chromatin structure and lengthens the cell cycle, especially G2. Surprisingly, removal of the H4 N terminus also derepresses the silent mating type loci, HML alpha and HMRa, disrupting mating. This activation is specific since other regulated genes (GAL10, PHO5, CUP1) are repressed and induced normally in these cells. Deletions of the hydrophilic N termini of H2A or H2B do not show this effect on mating. These experiments allow us to define a unique H4 function that is not shared by other histones (H2A and H2B).
通过删除这种高度保守的102个氨基酸的蛋白质片段，在体内探究酵母组蛋白H4的功能。H4疏水核心区域的缺失是致死性的，并会阻断染色体分离。相反，亲水的N端（第4 - 28位氨基酸残基）和C端（第100 - 102位氨基酸残基）的缺失是可行的。然而，N端缺失会改变正常的染色质结构并延长细胞周期，尤其是G2期。令人惊讶的是，去除H4的N端也会解除对沉默交配型基因座HMLα和HMRa的抑制，从而破坏交配。这种激活是特异性的，因为其他受调控的基因（GAL10、PHO5、CUP1）在这些细胞中正常地被抑制和诱导。H2A或H2B亲水N端的缺失对交配没有这种影响。这些实验使我们能够定义一种独特的H4功能，而其他组蛋白（H2A和H2B）并不具备这种功能。
