Santos Clelton A, Morais Mariana A B, Mandelli Fernanda, Lima Evandro A, Miyamoto Renan Y, Higasi Paula M R, Araujo Evandro A, Paixão Douglas A A, Junior Joaquim M, Motta Maria L, Streit Rodrigo S A, Morão 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
Brazilian Biorenewables National Laboratory (LNBR), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Brazil.
Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Brazil.
Nature. 2025 Mar;639(8056):1076-1083. doi: 10.1038/s41586-024-08553-z. Epub 2025 Feb 12.
The breakdown of cellulose is one of the most important reactions in nature and is central to biomass conversion to fuels and chemicals. However, the microfibrillar organization of cellulose and its complex interactions with other components of the plant cell wall poses a major challenge for enzymatic conversion. 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 recalcitrance. 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.
纤维素的分解是自然界中最重要的反应之一，也是生物质转化为燃料和化学品的核心环节。然而，纤维素的微纤维组织及其与植物细胞壁其他成分的复杂相互作用对酶促转化构成了重大挑战。在此，通过挖掘专门降解木质纤维素的微生物群落的宏基因组“暗物质”（功能未知的未分类DNA），我们发现了一种能氧化裂解纤维素的金属酶。这种金属酶通过具有C1区域选择性的外切型机制作用于纤维素，仅产生纤维二糖酸作为产物。晶体结构显示，催化铜埋在一个紧凑的果冻卷支架中，该支架具有一个扁平的纤维素结合位点。这种金属酶呈现同二聚体结构，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相互作用。表达这种金属酶的里氏木霉工程菌株的分泌组在工业相关条件下提高了预处理木质纤维素生物质中葡萄糖的释放量，证明了其生物技术潜力。这一发现改变了目前对致力于克服生物质顽固性的细菌氧化还原酶系统的理解。此外，它还能将农业工业残留物转化为高附加值的生物产品，从而有助于向可持续的生物基经济转型。
