Characterization and engineering of a plastic-degrading aromatic polyesterase.
Characterization and engineering of a plastic-degrading aromatic polyesterase.
复制标题
DOI：
10.1073/pnas.1718804115
复制
发表时间：
2018-05-08
影响因子：
11.1
通讯作者：
Beckham GT
中科院分区：
文献类型：
--
作者：
Austin HP;Allen MD;Donohoe BS;Rorrer NA;Kearns FL;Silveira RL;Pollard BC;Dominick G;Duman R;El Omari K;Mykhaylyk V;Wagner A;Michener WE;Amore A;Skaf MS;Crowley MF;Thorne AW;Johnson CW;Woodcock HL;McGeehan JE;Beckham GT
合成聚合物在现代世界无处不在，但却造成了全球环境问题。虽然聚对苯二甲酸乙二醇酯 (PET) 等塑料用途广泛，但它们对自然降解的抵抗力给动植物带来了严重且日益严重的风险，特别是在海洋环境中。在这里，我们表征了一种新发现的酶的 3D 结构，这种酶可以消化高度结晶的 PET，这是用于制造一次性塑料饮料瓶、某些服装和地毯的主要材料。我们设计了这种酶以提高 PET 降解能力，并进一步证明它还可以降解重要的 PET 替代品聚乙烯-2,5-呋喃二甲酸乙二醇酯，为生物基塑料回收提供新的机会。聚对苯二甲酸乙二醇酯 (PET) 是产量最丰富的合成聚合物之一，并且随着废弃的包装和纺织品以惊人的速度在环境中积累。 PET 如此有用的特性还赋予它惊人的抗生物降解性，可能在环境中持续几个世纪。我们对 PET 和其他塑料的集体依赖意味着，除非找到解决方案，否则这种积累将继续下去。最近，一种新发现的细菌 Ideonella sakaiensis 201-F6 被证明具有在 PET 作为主要碳和能源上生长的罕见能力。其 PET 生物降解能力的核心是分泌型 PETase（PET 消化酶）。在这里，我们展示了 PETase 的 0.92 Å 分辨率 X 射线晶体结构，它揭示了角质酶和脂肪酶的共同特征。 PETase 保留了祖先的 α/β-水解酶折叠，但表现出比同源角质酶更开放的活性位点裂缝。通过将两个活性位点残基突变为角质酶中的保守氨基酸来缩小结合裂缝，我们令人惊讶地观察到 PET 降解得到改善，这表明 PETase 并未针对结晶 PET 降解进行完全优化，尽管可能是在富含 PET 的环境中进化的。此外，我们还发现 PETase 可以降解另一种半芳香族聚酯，即聚乙烯 2,5-呋喃二甲酸 (PEF)，这是一种新兴的生物源 PET 替代品，具有改进的阻隔性能。相比之下，PETase 不会降解脂肪族聚酯，这表明它通常是一种芳香族聚酯酶。这些发现表明，通过额外的蛋白质工程来提高 PETase 性能是现实的，并强调需要进一步开发合成聚酯生物降解的结构/活性关系。
Synthetic polymers are ubiquitous in the modern world but pose a global environmental problem. While plastics such as poly(ethylene terephthalate) (PET) are highly versatile, their resistance to natural degradation presents a serious, growing risk to fauna and flora, particularly in marine environments. Here, we have characterized the 3D structure of a newly discovered enzyme that can digest highly crystalline PET, the primary material used in the manufacture of single-use plastic beverage bottles, in some clothing, and in carpets. We engineer this enzyme for improved PET degradation capacity and further demonstrate that it can also degrade an important PET replacement, polyethylene-2,5-furandicarboxylate, providing new opportunities for biobased plastics recycling. Poly(ethylene terephthalate) (PET) is one of the most abundantly produced synthetic polymers and is accumulating in the environment at a staggering rate as discarded packaging and textiles. The properties that make PET so useful also endow it with an alarming resistance to biodegradation, likely lasting centuries in the environment. Our collective reliance on PET and other plastics means that this buildup will continue unless solutions are found. Recently, a newly discovered bacterium, Ideonella sakaiensis 201-F6, was shown to exhibit the rare ability to grow on PET as a major carbon and energy source. Central to its PET biodegradation capability is a secreted PETase (PET-digesting enzyme). Here, we present a 0.92 Å resolution X-ray crystal structure of PETase, which reveals features common to both cutinases and lipases. PETase retains the ancestral α/β-hydrolase fold but exhibits a more open active-site cleft than homologous cutinases. By narrowing the binding cleft via mutation of two active-site residues to conserved amino acids in cutinases, we surprisingly observe improved PET degradation, suggesting that PETase is not fully optimized for crystalline PET degradation, despite presumably evolving in a PET-rich environment. Additionally, we show that PETase degrades another semiaromatic polyester, polyethylene-2,5-furandicarboxylate (PEF), which is an emerging, bioderived PET replacement with improved barrier properties. In contrast, PETase does not degrade aliphatic polyesters, suggesting that it is generally an aromatic polyesterase. These findings suggest that additional protein engineering to increase PETase performance is realistic and highlight the need for further developments of structure/activity relationships for biodegradation of synthetic polyesters.
登录
查看更多内容
影响因子：
13.6
作者：
Geyer R;Jambeck JR;Law KL
通讯作者：
Law KL
影响因子：
15
作者：
Knott, Brandon C.;Momeni, Majid Haddad;Beckham, Gregg T.
通讯作者：
Beckham, Gregg T.
影响因子：
56.9
作者：
Jambeck, Jenna R.;Geyer, Roland;Law, Kara Lavender
通讯作者：
Law, Kara Lavender
影响因子：
32.5
作者：
Eerhart, A. J. J. E.;Faaij, A. P. C.;Patel, M. K.
通讯作者：
Patel, M. K.
影响因子：
5.5
作者：
Acero, Enrique Herrero;Ribitsch, Doris;Guebitz, Georg
通讯作者：
Guebitz, Georg