Genetic Recombination by E. coli's RecBCD Pathway

同源染色体通过以下方式彼此交换片段： “广义基因重组”“这个过程尤其 由于其物理特性， 简单性和我们对病毒的深入了解。 我们的工作 已经确定了四种确定的酶中的每一种 在λ中影响重组的途径被DNA刺激 双链断裂，并建议认为，所有自发 广义重组依赖于这种断裂。 的 这些因素在所有途径中所起的作用并不相同。 在 三个途径（“红色样途径”）， 直接参与重组事件， 其他途径（RecBCD），断裂作为一个进入位点， 沿着DNA运动的酶，在DNA后产生重组作用 被一个特定的核苷酸序列（Chi）激活， 任意的距离。 对于这两种途径 已经提供了高度定义的模型。 该补助金旨在 测试这些模型和它们的替代版本。 一个统一 模型假设，在这两种类型的途径同源配对， 在离双链体任意距离处的双链体之间建立 双断链 在类红细胞通路中，这些区域 配对致力于通过降解一个 从切割到配对区域的切割分子的链。 在RecBCD途径中，RecBCD酶，它进入 切割，解析这些区域而不重组，除非 酶失去了D亚基作为传递Chi或 类Chi-like序列。

Homologous chromosomes exchange segments with each other via "generalized genetic recombination." This process is especially accessible in the bacterial virus lambda because of its physical simplicity and our intimate knowledge of that virus. Our work has established that each of the four identified enzymatic pathways that effect recombination in lambda is stimulated by DNA double-chain breaks and suggests the view that all spontaneous generalized recombination is dependent upon such breaks. The role played by these is not the same in all the pathways. In three of the pathways ("Red-like pathways") the breaks participate directly in the recombination event while in the other pathway (RecBCD) the break acts as an entry site for an enzyme that moves along the DNA effecting recombination after it is activated by a specific nucleotide sequence (Chi) at an arbitrary distance from the break. For both types of pathway highly defined models have been offered. This grant seeks to test those models and alternate versions of them. A unifying model supposes that in both types of pathway homologous pairing is established between duplexes at arbitrary distance from the double chain-break. In Red-like pathways, these regions of pairing are committed to recombination by degradation of one chain of the cut molecule from the cut to the region of pairing. In the RecBCD pathway, the RecBCD enzyme, which enters at the cut, resolves these regions without recombination, unless the enzyme has lost the D subunit as a result of passing Chi or a Chi-like sequence.