Kipling D, Tambini C, Kearsey S E
Department of Zoology, University of Oxford, UK.
Nucleic Acids Res. 1991 Apr 11;19(7):1385-91. doi: 10.1093/nar/19.7.1385.
In an attempt to identify trans-acting factors involved in replication origin function, we have characterized the RAR3 and RAR5 genes, identified by mutations which increase the mitotic stability of artificial chromosomes whose replication is dependent on the activity of weak ARS elements. Sequence analysis has shown that the RAR3 gene is identical to GAL11/SPT13, which encodes a putative transcription factor involved in the expression of a wide range of genes. Change-of-function mutations that truncate the RAR3 protein appear to be required to enhance chromosome stability. In contrast, loss of the RAR5 protein results in enhanced chromosome stability, as if the protein is an inhibitor of ARS function. The RAR5 gene encodes the 175 kDa DNA strand transfer protein beta, an activity that can promote the transfer of a strand from a double-stranded DNA molecule to a complementary single strand. This observation implies that a presumed recombination activity can affect eukaryotic chromosomal replication.
为了鉴定参与复制起点功能的反式作用因子，我们对RAR3和RAR5基因进行了表征，这些基因是通过增加人工染色体有丝分裂稳定性的突变鉴定出来的，这些人工染色体的复制依赖于弱ARS元件的活性。序列分析表明，RAR3基因与GAL11/SPT13相同，后者编码一种假定的转录因子，参与多种基因的表达。似乎需要截断RAR3蛋白的功能改变突变来增强染色体稳定性。相反，RAR5蛋白的缺失导致染色体稳定性增强，就好像该蛋白是ARS功能的抑制剂。RAR5基因编码175 kDa的DNA链转移蛋白β，该活性可以促进一条链从双链DNA分子转移到互补单链。这一观察结果表明，一种假定的重组活性可以影响真核染色体复制。
