Trans- and cis-acting elements for the replication of P1 miniplasmids.
Trans- and cis-acting elements for the replication of P1 miniplasmids.
复制标题
用于 P1 小质粒复制的反式和顺式作用元件。
DOI：
10.1016/0022-2836(85)90212-8
复制
发表时间：
1985
影响因子：
5.6
通讯作者：
Abeles,AL
中科院分区：
文献类型：
--
作者：
Austin,SJ;Mural,RJ;Chattoraj,DK;Abeles,AL
Replication-deficient mutants of the unit-copy miniplasmid λ-P1:5R were isolated after hydroxylamine mutagenesis. Complementation tests showed that the majority of these mutants are defective in the production of therepAprotein product. Two of these mutants have suppressible nonsense (amber) mutations. The DNA sequence of one of these,repA103, has been determined. The lesion lies within therepAopen reading frame, showing that therepAproduct is essential for plasmid replication. Complementation of deletion mutants of λ-P1:5R byrepAprotein showed that the origin of replication lies to the left ofrepAand that this 300-base-pair origin region is the only portion of the DNA essential for plasmid replication ifrepAprotein is suppliedin trans.Six of the 21 hydroxylamine-induced mutants were not complemented byrepA. Replication of three of these could be restored by introduction into the plasmid of a wildtype origin region, suggesting that they were origin-defective. The DNA sequence of two mutants was determined. Mutantrep-11has a 43-base-pair deletion within theincCsequence (incCis a series of five direct repeats of a 19-base-pair sequence known to be involved in the regulation of plasmid replication). The deletion appears to have been generated by homologous recombination between two repeats. Mutantrep-30has a single base substitution in a region just to the left ofincCthat destroys one of five G-A-T-C (dammethylation) sites in this region. As λ-P1:5R is unable to establish itself as a plasmid in a methylase-defective (dam−) strain, it seems probable that methylation of the G-A-T-C sequences is important for origin function. TheincCregion and the sequences to its left appear to constitute an essential part of the origin of replication.
