Roberts Eric M, Yuan Kai, Chaves Arielle M, Pierce Ethan T, Cresswell Rosalie, Dupree Ray, Yu Xiaolan, Blanton Richard L, Wu Shu-Zon, Bezanilla Magdalena, Dupree Paul, Haigler Candace H, Roberts Alison W
Department of Biology, Rhode Island College, Providence, RI 02908, USA.
Department of Biological Sciences, University of Rhode Island, Kingston, RI 02881, USA.
Sci Adv. 2024 Dec 13;10(50):eadr5188. doi: 10.1126/sciadv.adr5188.
Similar to cellulose synthases (CESAs), cellulose synthase-like D (CSLD) proteins synthesize β-1,4-glucan in plants. CSLDs are important for tip growth and cytokinesis, but it was unknown whether they form membrane complexes in vivo or produce microfibrillar cellulose. We produced viable CESA-deficient mutants of the moss to investigate CSLD function without interfering CESA activity. Microscopy and spectroscopy showed that CESA-deficient mutants synthesize cellulose microfibrils that are indistinguishable from those in vascular plants. Correspondingly, freeze-fracture electron microscopy revealed rosette-shaped particle assemblies in the plasma membrane that are indistinguishable from CESA-containing rosette cellulose synthesis complexes (CSCs). Our data show that proteins other than CESAs, most likely CSLDs, produce cellulose microfibrils in protonemal filaments. The data suggest that the specialized roles of CSLDs in cytokinesis and tip growth are based on differential expression and different interactions with microtubules and possibly Ca, rather than structural differences in the microfibrils they produce.
与纤维素合酶（CESA）类似，类纤维素合酶D（CSLD）蛋白在植物中合成β-1,4-葡聚糖。CSLD对顶端生长和胞质分裂很重要，但尚不清楚它们在体内是否形成膜复合物或产生微纤丝状纤维素。我们构建了苔藓中可行的CESA缺陷型突变体，以在不干扰CESA活性的情况下研究CSLD的功能。显微镜和光谱分析表明，CESA缺陷型突变体合成的纤维素微纤丝与维管植物中的无法区分。相应地，冷冻蚀刻电子显微镜显示质膜中有玫瑰花结状颗粒组装体，与含CESA的玫瑰花结纤维素合成复合物（CSC）无法区分。我们的数据表明，除CESA外的其他蛋白质，很可能是CSLD，在原丝体丝中产生纤维素微纤丝。数据表明，CSLD在胞质分裂和顶端生长中的特殊作用是基于差异表达以及与微管和可能的Ca的不同相互作用，而不是它们产生的微纤丝的结构差异。
