Halverson D, Gutkin G, Clarke L
Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara 93106, USA.
Mol Gen Genet. 2000 Nov;264(4):492-505. doi: 10.1007/s004380000338.
We previously used a genetic approach to identify a new class of Schizosaccharomyces pombe genes (chromosome loss when overexpressed; clo genes) that, when present in elevated dosage, cause the loss of an otherwise stable cen1 linear minichromosome at high rates. Here we report the identities of two clo genes; one encodes histone H3.3 and the other, designated clo2, encodes a novel protein with significant homology to fission yeast Swi6p, human and Drosophila HP1 heterochromatin proteins, and other chromo domain-containing proteins. Members of this group have been shown to localize to heterochromatic DNA, including centromeres, and to play roles in chromatin formation and organization. The S. pombe Clo2 protein localizes to centromere DNA in vivo, and overexpression of clo2 leads to a dramatic increase in the rate of mitotic loss of an artificial chromosome. Clo2p is not essential for mitotic growth, however, even in cells that also lack Swi6p. Thus, fission yeast appears to utilize multiple, functionally redundant, HP1-related proteins for heterochromatin-associated activities at centromeres and perhaps elsewhere in the genome.
我们之前采用遗传学方法鉴定了粟酒裂殖酵母中的一类新基因（过表达时染色体丢失；clo基因），当这些基因以高剂量存在时，会导致原本稳定的cen1线性小染色体以高频率丢失。在此我们报告两个clo基因的身份；一个编码组蛋白H3.3，另一个命名为clo2，编码一种与裂殖酵母Swi6p、人类和果蝇HP1异染色质蛋白以及其他含染色质结构域蛋白具有显著同源性的新蛋白。该蛋白家族成员已被证明定位于异染色质DNA，包括着丝粒，并在染色质形成和组织中发挥作用。粟酒裂殖酵母Clo2蛋白在体内定位于着丝粒DNA，clo2的过表达导致人工染色体有丝分裂丢失率显著增加。然而，Clo2p对于有丝分裂生长并非必需，即使在同时缺乏Swi6p的细胞中也是如此。因此，裂殖酵母似乎利用多种功能冗余的、与HP1相关的蛋白来进行着丝粒以及可能基因组其他位置的异染色质相关活动。
