Ohno S, Becak M L
Beckman Research Institute of the City of Hope, Duarte, CA 91010-0269.
Proc Natl Acad Sci U S A. 1993 Aug 1;90(15):7341-5. doi: 10.1073/pnas.90.15.7341.
The amino- and carboxyl-terminal regions of H1 histone are afforded an opportunity to bind to their own coding segments. While such binding is of no consequence to the type of H1 histone that is expressed only in terminally differentiated cells (here referred to as H5), the same binding occurring in H1 of proliferating cells might affect the course of evolution of its amino- and carboxyl-terminal regions. With the above in mind, amino acid sequences of H5 from three species were compared with those of H1 from five species. The spherical core was more conserved in H1 than in H5, whereas the amino- and carboxyl-terminal regions of both were hypervariable. A distinct evolutionary pattern, however, was observed only in these regions of H1 but not of H5. Tandem repeats of short palindromes often generated nearly identical long palindromes in distantly related species. Thus, as far as the 37-residue-long amino-terminal region was concerned, the greatest homology was between the rat and human rather than between the rat and the mouse. With regard to the last 25 residues in the carboxyl-terminal region, the greatest homology was between the chicken and the rainbow trout; the next was between the mouse and the trout. Successions of long palindromes populating the amino- and carboxyl-terminal regions of H1 might be the direct consequence of the autologous binding between peptides and their coding sequence.
H1组蛋白的氨基末端和羧基末端区域有机会与其自身的编码片段结合。虽然这种结合对于仅在终末分化细胞中表达的H1组蛋白（此处称为H5）的类型没有影响，但在增殖细胞的H1中发生的相同结合可能会影响其氨基末端和羧基末端区域的进化过程。基于上述考虑，将三个物种的H5氨基酸序列与五个物种的H1氨基酸序列进行了比较。球形核心在H1中比在H5中更保守，而两者的氨基末端和羧基末端区域都是高度可变的。然而，仅在H1的这些区域中观察到了独特的进化模式，而在H5中未观察到。短回文的串联重复序列在远缘物种中常常产生几乎相同的长回文序列。因此，就37个残基长的氨基末端区域而言，大鼠和人类之间的同源性最高，而不是大鼠和小鼠之间。关于羧基末端区域的最后25个残基，鸡和虹鳟之间的同源性最高；其次是小鼠和鳟鱼之间。填充H1氨基末端和羧基末端区域的长回文序列的连续出现可能是肽与其编码序列之间自体结合的直接结果。
