Research Center of Micro-Nano Technology, Hosei University, Koganei, Tokyo, Japan.
Department of Frontier Bioscience, Hosei University, Koganei, Tokyo, Japan.
Sci Rep. 2017 Sep 12;7(1):11426. doi: 10.1038/s41598-017-11796-8.
Gene rearrangement is a widely-shared phenomenon in spore forming bacteria, in which prophage(-like) elements interrupting sporulation-specific genes are excised from the host genome to reconstitute the intact gene. Here, we report a novel class of gene-intervening elements, named gin, inserted in the 225 bp gerE-coding region of the B. cereus ATCC10987 genome, which generates a sporulation-specific rearrangement. gin has no phage-related genes and possesses three site-specific recombinase genes; girA, girB, and girC. We demonstrated that the gerE rearrangement occurs at the middle stage of sporulation, in which site-specific DNA recombination took place within the 9 bp consensus sequence flanking the disrupted gerE segments. Deletion analysis of gin uncovered that GirC and an additional factor, GirX, are responsible for gerE reconstitution. Involvement of GirC and GirX in DNA recombination was confirmed by an in vitro recombination assay. These results broaden the definition of the sporulation-specific gene rearrangement phenomenon: gene-intervening elements are not limited to phage DNA but may include non-viral genetic elements that carry a developmentally-regulated site-specific recombination system.
基因重排是一种在产芽孢细菌中广泛存在的现象，其中，噬菌体（样）元件会从宿主基因组中切除中断孢子形成特异性基因的部分，以重新构建完整的基因。在这里，我们报告了一类新的基因干预元件，命名为 gin，插入到芽孢杆菌 ATCC10987 基因组的 225bp gerE 编码区，该元件会导致孢子形成特异性重排。gin 没有噬菌体相关基因，却拥有三个位点特异性重组酶基因：girA、girB 和 girC。我们证明，gerE 重排在孢子形成的中期发生，在该阶段，位于被破坏的 gerE 片段侧翼的 9bp 共有序列内会发生位点特异性 DNA 重组。gin 的缺失分析揭示，GirC 和一个额外的因子 GirX 负责 gerE 的重组。体外重组实验证实了 GirC 和 GirX 参与 DNA 重组。这些结果扩展了孢子形成特异性基因重排现象的定义：基因干预元件不仅限于噬菌体 DNA，还可能包括携带发育调控位点特异性重组系统的非病毒遗传元件。
