巴西生物可再生能源国家实验室Mario T. Murakami课题组在研究中取得进展。他们的研究开发出了一种宏基因组“暗物质”酶催化氧化纤维素转化。2025年2月12日，国际知名学术期刊《自然》发表了这一成果。

通过挖掘专门从事木质纤维素降解的微生物群落的宏基因组“暗物质”（未分类的DNA，功能未知），研究人员发现了一种氧化切割纤维素的金属酶。这种金属酶通过具有C1区选择性的外显型机制作用于纤维素，产生纤维素酸作为产物。晶体结构揭示了埋在紧凑的果冻状支架中的催化铜，该支架具有扁平的纤维素结合位点。这种金属酶表现出同二聚体的结构，使一个亚基能够原位生成过氧化氢，而另一个亚基则与纤维素有效地相互作用。在相关条件下，表达该金属酶的里氏木霉工程菌株的分泌组促进了预处理木质纤维素生物质中葡萄糖的释放，显示了其生物技术潜力。这一发现改变了目前对细菌氧化还原酶系统的理解，该系统致力于克服生物量的顽固性。

此外，它能够将农工残留物转化为增值生物产品，从而有助于向可持续和生物经济过渡。

据悉，纤维素的分解是自然界最重要的反应之一，是生物质转化为燃料和化学品的关键。然而，纤维素的微纤维组织及其与植物细胞壁其他组分的复杂相互作用对酶转化构成了重大挑战。

附：英文原文

Title: A metagenomic ‘dark matter’ enzyme catalyses oxidative cellulose conversion

Author: Santos, Clelton A., Morais, Mariana A. B., Mandelli, Fernanda, Lima, Evandro A., Miyamoto, Renan Y., Higasi, Paula M. R., Araujo, Evandro A., Paixo, Douglas A. A., Junior, Joaquim M., Motta, Maria L., Streit, Rodrigo S. A., Moro, Luana G., Silva, Claudio B. C., Wolf, Lucia D., Terrasan, Cesar R. F., Bulka, Nathalia R., Diogo, Jose A., Fuzita, Felipe J., Colombari, Felippe M., Santos, Camila R., Rodrigues, Priscila T., Silva, Daiane B., Grisel, Sacha, Bernardes, Juliana S., Terrapon, Nicolas, Lombard, Vincent, Filho, Antonio J. C., Henrissat, Bernard, Bissaro, Bastien, Berrin, Jean-Guy, Persinoti, Gabriela F., Murakami, Mario T.

Issue&Volume: 2025-02-12

Abstract: The breakdown of cellulose is one of the most important reactions in nature1,2 and is central to biomass conversion to fuels and chemicals3. However, the microfibrillar organization of cellulose and its complex interactions with other components of the plant cell wall poses a major challenge for enzymatic conversion4. Here, by mining the metagenomic ‘dark matter’ (unclassified DNA with unknown function) of a microbial community specialized in lignocellulose degradation, we discovered a metalloenzyme that oxidatively cleaves cellulose. This metalloenzyme acts on cellulose through an exo-type mechanism with C1 regioselectivity, resulting exclusively in cellobionic acid as a product. The crystal structure reveals a catalytic copper buried in a compact jelly-roll scaffold that features a flattened cellulose binding site. This metalloenzyme exhibits a homodimeric configuration that enables in situ hydrogen peroxide generation by one subunit while the other is productively interacting with cellulose. The secretome of an engineered strain of the fungus Trichoderma reesei expressing this metalloenzyme boosted the glucose release from pretreated lignocellulosic biomass under industrially relevant conditions, demonstrating its biotechnological potential. This discovery modifies the current understanding of bacterial redox enzymatic systems devoted to overcoming biomass recalcitrance5,6,7. Furthermore, it enables the conversion of agro-industrial residues into value-added bioproducts, thereby contributing to the transition to a sustainable and bio-based economy.

DOI: 10.1038/s41586-024-08553-z

Source: https://www.nature.com/articles/s41586-024-08553-z