Commonwealth Scientific and Industrial Research Organization Plant Industry, Canberra, Australian Capital Territory 2601, Australia.
Plant Physiol. 2011 Sep;157(1):40-54. doi: 10.1104/pp.111.178574. Epub 2011 Jul 14.
Sucrose (Suc) synthase (Sus) is the major enzyme of Suc breakdown for cellulose biosynthesis in cotton (Gossypium hirsutum) fiber, an important source of fiber for the textile industry. This study examines the tissue-specific expression, relative abundance, and temporal expression of various Sus transcripts and proteins present in cotton. A novel isoform of Sus (SusC) is identified that is expressed at high levels during secondary cell wall synthesis in fiber and is present in the cell wall fraction. The phylogenetic relationships of the deduced amino acid sequences indicate two ancestral groups of Sus proteins predating the divergence of monocots and dicots and that SusC sequences form a distinct branch in the phylogeny within the dicot-specific clade. The subcellular location of the Sus isoforms is determined, and it is proposed that cell wall-localized SusC may provide UDP-glucose for cellulose and callose synthesis from extracellular sugars.
蔗糖合酶（Sus）是棉花（Gossypium hirsutum）纤维中纤维素生物合成的主要蔗糖分解酶，是纺织工业纤维的重要来源。本研究探讨了棉花中各种 Sus 转录本和蛋白的组织特异性表达、相对丰度和时间表达。鉴定出一种新型 Sus 同工型（SusC），在纤维次生细胞壁合成过程中高水平表达，并存在于细胞壁部分。推导的氨基酸序列的系统发育关系表明，Sus 蛋白有两个祖先进化群，早于单子叶植物和双子叶植物的分化，而 SusC 序列在双子叶植物特有的进化枝内形成一个独特的分支。Sus 同工型的亚细胞定位被确定，并提出细胞壁定位的 SusC 可能从细胞外糖为纤维素和胼胝质合成提供 UDP-葡萄糖。
