Characterization of a novel origin recognition complex-like complex: implications for DNA recognition, cell cycle control, and locus-specific gene amplification.
Characterization of a novel origin recognition complex-like complex: implications for DNA recognition, cell cycle control, and locus-specific gene amplification.
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新型起源识别复合物样复合物的表征：对 DNA 识别、细胞周期控制和位点特异性基因扩增的影响。
DOI：
10.1128/mcb.23.14.5005-5017.2003
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发表时间：
2003
影响因子：
5.3
通讯作者：
Kapler,GeoffreyM
中科院分区：
文献类型：
--
作者：
Mohammad,Mohammad;York,RandallD;Hommel,Jonathan;Kapler,GeoffreyM
起始识别复合物（origin recognition complex，ORC）在真核生物DNA复制中起着重要作用。在这里，我们描述了一个独特的ORC样复合物inTetrahymena thermophila，TIF 4，它结合在一个ATP依赖的方式所需的序列细胞周期控制的复制和基因扩增（核糖体DNA [rDNA] I型元件）。TIF4的DNA识别模式与其他特征性的ORC不同，因为它只与单链DNA结合。与酵母ORC相反，TIF 4 DNA结合活性受细胞周期调节，并在S期达到峰值，与Orc2相关亚基p69从细胞质到大核的再分布一致。起源结合活性和核p69免疫反应性在发展过程中进一步调节，在那里他们区分复制非复制核。这两种活动都失去了从生殖细胞微核程序逮捕微核复制。在野生型细胞的整个发育过程中，用Orc2抗体染色的复制大核，但在扩增缺陷型mm11突变体中未能做到这一点。总的来说，这些发现表明TIF4的调节与细胞周期和发育编程的复制周期密切相关。他们进一步暗示TIF4参与rDNA基因扩增。由于I型元件与其他序列特异性单链断裂（体外和体内）相互作用，Orc样（TIF4）和非ORC样蛋白与此复制决定簇的动态相互作用可能提供一种新的调控机制。
The origin recognition complex (ORC) plays a central role in eukaryotic DNA replication. Here we describe a unique ORC-like complex inTetrahymena thermophila, TIF4, which bound in an ATP-dependent manner to sequences required for cell cycle-controlled replication and gene amplification (ribosomal DNA [rDNA] type I elements). TIF4's mode of DNA recognition was distinct from that of other characterized ORCs, as it bound exclusively to single-stranded DNA. In contrast to yeast ORCs, TIF4 DNA binding activity was cell cycle regulated and peaked during S phase, coincident with the redistribution of the Orc2-related subunit, p69, from the cytoplasm to the macronucleus. Origin-binding activity and nuclear p69 immunoreactivity were further regulated during development, where they distinguished replicating from nonreplicating nuclei. Both activities were lost from germ line micronuclei following the programmed arrest of micronuclear replication. Replicating macronuclei stained with Orc2 antibodies throughout development in wild-type cells but failed to do so in the amplification-defectivermm11mutant. Collectively, these findings indicate that the regulation of TIF4 is intimately tied to the cell cycle and developmentally programmed replication cycles. They further implicate TIF4 in rDNA gene amplification. As type I elements interact with other sequence-specific single-strand breaks (in vitro and in vivo), the dynamic interplay of Orc-like (TIF4) and non-ORC-like proteins with this replication determinant may provide a novel mechanism for regulation.