Hydrocarbons Are Essential for Optimal Cell Size, Division, and Growth of Cyanobacteria
Hydrocarbons Are Essential for Optimal Cell Size, Division, and Growth of Cyanobacteria
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DOI：
10.1104/pp.16.01205
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发表时间：
2016-11-01
期刊：
影响因子：
7.4
通讯作者：
Howe, Christopher J.
中科院分区：
文献类型：
--
作者：
Lea-Smith, David J.;Ortiz-Suarez, Maite L.;Howe, Christopher J.
蓝藻的组织错综复杂，将一系列内部类囊体膜(光合作用的场所)合并到不比其他细菌大的细胞中。他们还合成C15-C19烷烃和烯烃，这导致环境中大量产生碳氢化合物。所有测序的蓝藻都编码碳氢化合物的生物合成途径，这表明这些化合物具有重要的、未确定的生理作用。在这里，我们证明了聚球藻缺乏碳氢化合物的突变体。PCC7002和聚球藻sp.PCC6803表现出与野生型显著的表型差异，包括细胞体积增大，生长减慢，分裂缺陷增加。不同品系之间的光合作用速率相似，尽管在可溶性捕光藻胆体复合体和膜结合的光系统之间的能量转移略有减少。碳氢化合物在类囊体膜和细胞质膜中积累。膜的模拟表明，这些化合物聚集在脂质双层的中心，潜在地促进了膜的灵活性和促进了曲率。活体测量证实聚球藻。与野生型相比，缺少碳氢化合物的突变体PCC7002表现出较小的类囊体膜曲率。我们认为碳氢化合物可能在诱导细胞分裂、大小和生长以及可溶性蛋白和膜结合蛋白的有效结合所需的膜上的灵活性方面发挥作用。最近在微藻物种中发现了C15-C17烷烃和烯烃，这表明碳氢化合物在广泛的光合作用生物中可能具有类似的功能。
Cyanobacteria are intricately organized, incorporating an array of internal thylakoid membranes, the site of photosynthesis, into cells no larger than other bacteria. They also synthesize C15-C19 alkanes and alkenes, which results in substantial production of hydrocarbons in the environment. All sequenced cyanobacteria encode hydrocarbon biosynthesis pathways, suggesting an important, undefined physiological role for these compounds. Here, we demonstrate that hydrocarbon-deficient mutants of Synechococcus sp. PCC 7002 and Synechocystis sp. PCC 6803 exhibit significant phenotypic differences from wild type, including enlarged cell size, reduced growth, and increased division defects. Photosynthetic rates were similar between strains, although a minor reduction in energy transfer between the soluble light harvesting phycobilisome complex andmembrane-bound photosystems was observed. Hydrocarbons were shown to accumulate in thylakoid and cytoplasmic membranes. Modeling of membranes suggests these compounds aggregate in the center of the lipid bilayer, potentially promoting membrane flexibility and facilitating curvature. In vivo measurements confirmed that Synechococcus sp. PCC 7002 mutants lacking hydrocarbons exhibit reduced thylakoid membrane curvature compared to wild type. We propose that hydrocarbons may have a role in inducing the flexibility in membranes required for optimal cell division, size, and growth, and efficient association of soluble and membrane bound proteins. The recent identification of C15-C17 alkanes and alkenes in microalgal species suggests hydrocarbons may serve a similar function in a broad range of photosynthetic organisms.