Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, USA.
Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, USA.
J Bacteriol. 2019 Aug 8;201(17). doi: 10.1128/JB.00276-19. Print 2019 Sep 1.
Surface colonization is central to the lifestyles of many bacteria. Exploiting surface niches requires sophisticated systems for sensing and attaching to solid materials. synthesizes a polysaccharide-based adhesin known as the holdfast at one of its cell poles, which enables tight attachment to exogenous surfaces. The genes required for holdfast biosynthesis have been analyzed in detail, but difficulties in isolating analytical quantities of the adhesin have limited efforts to characterize its chemical structure. In this report, we describe a method to extract the holdfast from cultures and present a survey of its carbohydrate content. Glucose, 3--methylglucose, mannose, -acetylglucosamine, and xylose were detected in our extracts. Our results provide evidence that the holdfast contains a 1,4-linked backbone of glucose, mannose, -acetylglucosamine, and xylose that is decorated with branches at the C-6 positions of glucose and mannose. By defining the monosaccharide components in the polysaccharide, our work establishes a framework for characterizing enzymes in the holdfast pathway and provides a broader understanding of how polysaccharide adhesins are built. To colonize solid substrates, bacteria often deploy dedicated adhesins that facilitate attachment to surfaces. initiates surface colonization by secreting a carbohydrate-based adhesin called the holdfast. Because little is known about the chemical makeup of the holdfast, the pathway for its biosynthesis and the physical basis for its unique adhesive properties are poorly understood. This study outlines a method to extract the holdfast and describes the monosaccharide components contained within the adhesive matrix. The composition analysis adds to our understanding of the chemical basis for holdfast attachment and provides missing information needed to characterize enzymes in the biosynthetic pathway.
表面定植是许多细菌生活方式的核心。利用表面小生境需要复杂的系统来感知和附着在固体材料上。 合成一种多糖基黏附素，称为固着器，位于其细胞的一个极点，使其能够紧密附着在外源表面。固着器生物合成所需的基因已被详细分析，但由于难以分离分析量的黏附素，限制了对其化学结构进行特征描述的努力。在本报告中，我们描述了一种从 培养物中提取固着器的方法，并对其碳水化合物含量进行了调查。我们的提取物中检测到葡萄糖、3--甲基葡萄糖、甘露糖、乙酰葡萄糖胺和木糖。我们的结果提供了证据，表明固着器含有葡萄糖、甘露糖、乙酰葡萄糖胺和木糖的 1,4 键连接的主链，其在葡萄糖和甘露糖的 C-6 位置被支链修饰。通过确定多糖中的单糖成分，我们的工作为鉴定固着器途径中的酶建立了一个框架，并提供了对多糖黏附素如何构建的更广泛的理解。为了定植固体基质，细菌通常会部署专门的黏附素，以促进与表面的附着。 通过分泌一种称为固着器的基于碳水化合物的黏附素来启动表面定植。由于对固着器的化学组成知之甚少，其生物合成途径及其独特的黏附特性的物理基础了解甚少。本研究概述了一种提取 固着器的方法，并描述了黏附基质中包含的单糖成分。组成分析增加了我们对固着器附着的化学基础的理解，并提供了表征生物合成途径中酶所需的缺失信息。
