Cyanobacteria developed oxygenic photosynthesis and represent the phylogenetic ancestors of chloroplasts. The model strain Anabaena sp. strain PCC 7120 grows as filaments of communicating cells and can form heterocysts, cells specialized for N2 fixation. In the Anabaena genome, ORF all2390 is annotated as encoding a SulA homolog, but sequence similarity to SulA of model bacteria is insignificant. We generated strains that lacked or overexpressed all2390, both of which showed instances of increased cell size, and observed that purified All2390 protein interfered with the in vitro polymerization of FtsZ. Heterocyst frequency diminished by all2390 inactivation and increased by all2390 overexpression. Overexpression retarded the dismantlement of Z‐ring structures that determines commitment in the differentiating cells. Thus, All2390 can influence cell division affecting heterocyst differentiation. An All2390‐GFP fusion protein localized to the thylakoid membranes including the honeycomb membranes, which harbor photosynthetic complexes, in the heterocyst polar regions. Notably, all2390 expression strongly increased under high light, conditions under which growth of the null mutant is compromised. Thus, All2390 appears essential for adaptation to high light conditions. We named All2390 ThyD to reflect its thylakoidal localization and its dual role in cell division dynamics and acclimation of thylakoid membranes to increased light intensity.

中文翻译：

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ThyD 是一种类囊体膜蛋白，影响多细胞蓝藻 anabaena sp 中的细胞分裂和对强光的适应。菌株 PCC 7120


蓝细菌发展了含氧光合作用，代表了叶绿体的系统发育祖先。模型菌株 Anabaena sp. 菌株 PCC 7120 作为交通细胞的细丝生长，可以形成异囊，即专门用于 N2 固定的细胞。在 Anabaena 基因组中，ORF all2390 被注释为编码 SulA 同源物，但与模式细菌的 SulA 的序列相似性不显著。我们生成了缺乏或过表达 all2390 的菌株，这两种菌株都显示出细胞大小增加的实例，并观察到纯化的 All2390 蛋白干扰了 FtsZ 的体外聚合。异囊频率因 all2390 失活而降低，而因 all2390 过表达而增加。过表达延缓了决定分化细胞定型的 Z 环结构的分解。因此，All2390 可以影响影响异囊分化的细胞分裂。一种 All2390-GFP 融合蛋白，定位于异囊极性区域的类囊体膜，包括含有光合复合物的蜂窝膜。值得注意的是，all2390 表达在高光下强烈增加，在强光下，无效突变体的生长受到损害。因此，All2390 对于适应强光条件似乎至关重要。我们将 All2390 命名为 ThyD，以反映其类囊体定位及其在细胞分裂动力学和类囊体膜适应增加的光强度中的双重作用。