Grün Christian H, Hochstenbach Frans, Humbel Bruno M, Verkleij Arie J, Sietsma J Hans, Klis Frans M, Kamerling Johannis P, Vliegenthart Johannes F G
Bijvoet Center, Department of Bio-Organic Chemistry, Section of Glycoscience and Biocatalysis, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
Glycobiology. 2005 Mar;15(3):245-57. doi: 10.1093/glycob/cwi002. Epub 2004 Oct 6.
Morphology and structural integrity of fungal cells depend on cell wall polysaccharides. The chemical structure and biosynthesis of two types of these polysaccharides, chitin and (1-->3)-beta-glucan, have been studied extensively, whereas little is known about alpha-glucan. Here we describe the chemical structure of alpha-glucan isolated from wild-type and mutant cell walls of the fission yeast Schizosaccharomyces pombe. Wild-type alpha-glucan was found to consist of a single population of linear glucose polymers, approximately 260 residues in length. These glucose polymers were composed of two interconnected linear chains, each consisting of approximately 120 (1-->3)-linked alpha-d-glucose residues and some (1-->4)-linked alpha-D-glucose residues at the reducing end. By contrast, alpha-glucan of an alpha-glucan synthase mutant with an aberrant cell morphology and reduced alpha-glucan levels consisted of a single chain only. We propose that alpha-glucan biosynthesis involves an ordered series of events, whereby two alpha-glucan chains are coupled to create mature cell wall alpha-glucan. This mature form of cell wall alpha-glucan is essential for fission-yeast morphogenesis.
真菌细胞的形态和结构完整性取决于细胞壁多糖。其中两类多糖——几丁质和（1→3）-β-葡聚糖的化学结构和生物合成已得到广泛研究，而关于α-葡聚糖的了解却很少。在此，我们描述了从粟酒裂殖酵母野生型和突变型细胞壁中分离出的α-葡聚糖的化学结构。发现野生型α-葡聚糖由单一群体的线性葡萄糖聚合物组成，长度约为260个残基。这些葡萄糖聚合物由两条相互连接的线性链组成，每条链由约120个（1→3）连接的α-D-葡萄糖残基以及还原端的一些（1→4）连接的α-D-葡萄糖残基组成。相比之下，具有异常细胞形态和降低的α-葡聚糖水平的α-葡聚糖合酶突变体的α-葡聚糖仅由一条链组成。我们提出α-葡聚糖生物合成涉及一系列有序事件，即两条α-葡聚糖链偶联以形成成熟的细胞壁α-葡聚糖。这种成熟形式的细胞壁α-葡聚糖对于裂殖酵母的形态发生至关重要。
