Grodberg J, Salazar N, Oren R, Mirelman D
Department of Biophysics, Weizmann Institute of Science, Rehovot, Israel.
Nucleic Acids Res. 1990 Sep 25;18(18):5515-9. doi: 10.1093/nar/18.18.5515.
Entamoeba histolytica possesses a 24.5 kilobase plasmid-like molecule which encodes for the organism's ribosomal RNAs. Sequence analysis of this extrachromosomal element revealed the presence of AT rich sequences which show homology to the origin of replication of other lower eucaryotes. An 802 bp fragment containing these sequences was cloned into a yeast shuttle vector lacking the origin of replication and the construct tested for its ability to replicate autonomously in yeast. Mitotic stability tests as well as evidence for plasmid maintenance indicate that the transformed cells contained self-replicating episomes and not stably integrated molecules. The nucleotide sequence of this ARS-containing fragment is presented.
溶组织内阿米巴拥有一个24.5千碱基的类质粒分子，该分子编码该生物体的核糖体RNA。对这个染色体外元件的序列分析揭示了富含AT的序列的存在，这些序列与其他低等真核生物的复制起点具有同源性。一个包含这些序列的802 bp片段被克隆到一个缺乏复制起点的酵母穿梭载体中，并测试该构建体在酵母中自主复制的能力。有丝分裂稳定性测试以及质粒维持的证据表明，转化细胞含有自我复制的附加体，而不是稳定整合的分子。本文给出了这个含自主复制序列（ARS）片段的核苷酸序列。
