Department of Biology, Indiana University, Bloomington, IN 47405, USA.
Mol Microbiol. 2011 Apr;80(2):524-41. doi: 10.1111/j.1365-2958.2011.07590.x. Epub 2011 Mar 7.
Escherichia coli DNA polymerase IV, encoded by the dinB gene, is a member of the Y family of specialized DNA polymerases. Pol IV is capable of synthesizing past DNA lesions and may help to restart stalled replication forks. However, Pol IV is error-prone, contributing to both DNA damage-induced and stress-induced (adaptive) mutations. Here we demonstrate that Pol IV interacts in vitro with Rep DNA helicase and that this interaction enhances Rep's helicase activity. In addition, Pol IV polymerase activity is stimulated by interacting with Rep, and Pol IV β clamp-binding motif appears to be required for this stimulation. However, neither Rep's helicase activity nor its ability to bind DNA is required for it to stimulate Pol IV's polymerase activity. The interaction between Rep and Pol IV is biologically significant in vivo as Rep enhances Pol IV's mutagenic activity in stationary-phase cells. These data indicate a new role for Rep in contributing to Pol IV-dependent adaptive mutation. This functional interaction also provides new insight into how the cell might control or target Pol IV's mutagenic activity.
大肠杆菌 DNA 聚合酶 IV，由 dinB 基因编码，是 Y 家族专门的 DNA 聚合酶之一。聚合酶 IV 能够合成过去的 DNA 损伤，并可能有助于重新启动停滞的复制叉。然而，聚合酶 IV 易出错，导致 DNA 损伤诱导和应激诱导（适应性）突变。在这里，我们证明聚合酶 IV 在体外与 Rep DNA 解旋酶相互作用，并且这种相互作用增强了 Rep 的解旋酶活性。此外，聚合酶 IV 的聚合酶活性通过与 Rep 的相互作用而受到刺激，并且聚合酶 IV β 夹结合基序似乎是这种刺激所必需的。然而，Rep 的解旋酶活性及其与 DNA 结合的能力都不是刺激其聚合酶活性所必需的。Rep 与聚合酶 IV 之间的相互作用在体内具有生物学意义，因为 Rep 增强了聚合酶 IV 在静止期细胞中的诱变活性。这些数据表明 Rep 在促进聚合酶 IV 依赖性适应性突变中具有新的作用。这种功能相互作用还为细胞如何控制或靶向聚合酶 IV 的诱变活性提供了新的见解。
