Hyaluronan Molecular Weight Is Controlled by UDP-N-acetylglucosamine Concentration in Streptococcus zooepidemicus
Hyaluronan Molecular Weight Is Controlled by UDP-N-acetylglucosamine Concentration in Streptococcus zooepidemicus
复制标题
DOI：
10.1074/jbc.m109.011999
复制
发表时间：
2009-07-03
影响因子：
4.8
通讯作者：
Nielsen, Lars Keld
中科院分区：
文献类型：
--
作者：
Chen, Wendy Yiting;Marcellin, Esteban;Nielsen, Lars Keld
透明质酸的分子量对其流变学和生物学功能是重要的。链终止和分子量控制的分子机制仍然知之甚少，不仅对于透明质酸脱氢酶，而且对于其他β-多糖脱氢酶，如G.纤维素酶、几丁质酶和1，3-β葡聚糖酶。在这项工作中，我们操纵代谢物浓度的透明质酸途径过表达的五个基因的透明质酸合成操纵子在马链球菌亚种。小动物。参与UDP-葡萄糖醛酸生物合成的基因的过表达降低分子量，而参与UDP-N-乙酰葡糖胺生物合成的基因的过表达增加分子量。观察到的最高分子量为3.4 +/-0.1 MDa，是野生型菌株中观察到的1.8 +/-0.1 MDa的两倍。数据表明：（a）当UDP-N-乙酰葡糖胺和UDP-葡糖醛酸达到适当平衡时，达到高分子量，（B）UDP-N-乙酰葡糖胺对分子量发挥主导作用，和（c）野生型菌株具有次优水平的UDP-N-乙酰葡糖胺。与此一致，分子量与UDP-N-乙酰葡糖胺的浓度密切相关（rho = 0.84，p = 3 x 10（-5））。本文中提出的数据代表了第一个模型的基础上的活性糖前体的浓度透明质酸分子量控制。这些结果可用于工程菌株生产高分子量的透明质酸，并可能提供类似的聚合机制在其他多糖的洞察。
The molecular weight of hyaluronan is important for its rheological and biological function. The molecular mechanisms underlying chain termination and hence molecular weight control remain poorly understood, not only for hyaluronan synthases but also for other beta-polysaccharide synthases, e. g. cellulose, chitin, and 1,3-betaglucan synthases. In this work, we manipulated metabolite concentrations in the hyaluronan pathway by overexpressing the five genes of the hyaluronan synthesis operon in Streptococcus equi subsp. zooepidemicus. Overexpression of genes involved in UDP-glucuronic acid biosynthesis decreased molecular weight, whereas overexpression of genes involved in UDP-N-acetylglucosamine biosynthesis increased molecular weight. The highest molecular mass observed was at 3.4 +/- 0.1 MDa twice that observed in the wild-type strain, 1.8 +/- 0.1 MDa. The data indicate that (a) high molecular weight is achieved when an appropriate balance of UDP-N-acetylglucosamine and UDP-glucuronic acid is achieved, (b) UDP-N-acetylglucosamine exerts the dominant effect on molecular weight, and (c) the wild-type strain has suboptimal levels of UDP-Nacetylglucosamine. Consistent herewith molecular weight correlated strongly (rho = 0.84, p = 3 x 10(-5)) with the concentration of UDP-N-acetylglucosamine. Data presented in this paper represent the first model for hyaluronan molecular weight control based on the concentration of activated sugar precursors. These results can be used to engineer strains producing high molecular weight hyaluronan and may provide insight into similar polymerization mechanisms in other polysaccharides.