Bacterial cellulose biosynthesis: diversity of operons, subunits, products, and functions.
Bacterial cellulose biosynthesis: diversity of operons, subunits, products, and functions.
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DOI：
10.1016/j.tim.2015.05.005
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发表时间：
2015-09
影响因子：
15.9
通讯作者：
Galperin MY
中科院分区：
文献类型：
--
作者：
Römling U;Galperin MY
最近对细菌纤维素生物合成的研究，包括功能性纤维素合成酶复合体的结构特征，提供了对这一迷人过程的第一个机械洞察力。在大多数被研究的细菌中，只有两个亚基BCSA和BCSB是体外形成多糖链的必要条件和充分条件。不同分类群之间的其他亚基通过调节生物合成装置的表达、将新生的β-D-葡聚糖聚合物输出到细胞表面以及将纤维素纤维组织成更高级别的结构来影响体内的酶活性和产物产量。这些辅助亚基在决定所形成的生物膜的数量和结构方面起着关键作用，这对于细菌与高等生物的相互作用尤其重要，这种相互作用导致根际定植，并调节产生纤维素的细菌病原体在宿主细胞内外的毒力。在这里，我们回顾了在不同细菌基因组中发现的四种主要类型的纤维素合成酶操纵子的组织结构，识别了其他编码纤维素生物合成和分泌机制的可能组件的BCS基因，并提出了这些基因和亚单位的统一命名。我们还讨论了纤维素作为各种自由生活和致病细菌形成的生物膜的关键成分的作用，对于后者，在急性感染和宿主持久性之间的选择中。
Recent studies of bacterial cellulose biosynthesis, including structural characterization of a functional cellulose synthase complex, provided the first mechanistic insight into this fascinating process. In most studied bacteria, just two subunits, BcsA and BcsB, are necessary and sufficient for the formation of the polysaccharide chain in vitro. Other subunits – which differ among various taxa – affect the enzymatic activity and product yield in vivo by modulating expression of biosynthesis apparatus, export of the nascent β-D-glucan polymer to the cell surface, and the organization of cellulose fibers into a higher-order structure. These auxiliary subunits play key roles in determining the quantity and structure of the resulting biofilm, which is particularly important for interactions of bacteria with higher organisms that lead to rhizosphere colonization and modulate virulence of cellulose-producing bacterial pathogens inside and outside of host cells. Here we review the organization of four principal types of cellulose synthase operons found in various bacterial genomes, identify additional bcs genes that encode likely components of the cellulose biosynthesis and secretion machinery, and propose a unified nomenclature for these genes and subunits. We also discuss the role of cellulose as a key component of biofilms formed by a variety of free-living and pathogenic bacteria and, for the latter, in the choice between acute infection and persistence in the host.