Temple Henry, Saez-Aguayo Susana, Reyes Francisca C, Orellana Ariel
Centro de Biotecnología Vegetal, FONDAP Center for Genome Regulation, Facultad de Ciencias Biológicas, Universidad Andrés Bello, Avenida República 217, Santiago, RM 837-0146, Chile.
Centro de Biotecnología Vegetal, FONDAP Center for Genome Regulation, Facultad de Ciencias Biológicas, Universidad Andrés Bello, Avenida República 217, Santiago, RM 837-0146, Chile
Glycobiology. 2016 Sep;26(9):913-925. doi: 10.1093/glycob/cww054. Epub 2016 Aug 9.
The cell wall is a complex extracellular matrix composed primarily of polysaccharides. Noncellulosic polysaccharides, glycoproteins and proteoglycans are synthesized in the Golgi apparatus by glycosyltransferases (GTs), which use nucleotide sugars as donors to glycosylate nascent glycan and glycoprotein acceptors that are subsequently exported to the extracellular space. Many nucleotide sugars are synthesized in the cytosol, leading to a topological issue because the active sites of most GTs are located in the Golgi lumen. Nucleotide sugar transporters (NSTs) overcome this problem by translocating nucleoside diphosphate sugars from the cytosol into the lumen of the organelle. The structures of the cell wall components synthesized in the Golgi are diverse and complex; therefore, transporter activities are necessary so that the nucleotide sugars can provide substrates for the GTs. In this review, we describe the topology of reactions involved in polysaccharide biosynthesis in the Golgi and focus on the roles of NSTs as well as their impacts on cell wall structure when they are altered.
细胞壁是一种主要由多糖组成的复杂细胞外基质。非纤维素多糖、糖蛋白和蛋白聚糖在高尔基体中由糖基转移酶（GTs）合成，糖基转移酶使用核苷酸糖作为供体，对新生聚糖和糖蛋白受体进行糖基化，随后这些产物被输出到细胞外空间。许多核苷酸糖在细胞质中合成，这就导致了一个拓扑学问题，因为大多数糖基转移酶的活性位点位于高尔基体腔中。核苷酸糖转运蛋白（NSTs）通过将核苷二磷酸糖从细胞质转运到细胞器腔中来克服这个问题。在高尔基体中合成的细胞壁成分的结构多样且复杂；因此，转运蛋白的活性是必需的，以便核苷酸糖能够为糖基转移酶提供底物。在这篇综述中，我们描述了高尔基体中多糖生物合成所涉及反应的拓扑结构，并重点关注核苷酸糖转运蛋白的作用以及它们发生改变时对细胞壁结构的影响。
