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[前沿资讯 ] 北京大学生命科学学院阐明磷酸化酶激酶PhK的组装与激活机制 进入全文
北京大学
PhK是第一个被纯化的蛋白激酶，也是最大、最复杂的蛋白激酶之一，总分子量为1.3兆道尔顿。它包含α、β、γ和δ四个亚基。其中，α和β亚基是结构亚基；γ亚基具有激酶活性，由一个持续激活的N端激酶结构域（KD）和一个C端调节结构域（CRD）组成；δ亚基为钙调蛋白，但其特殊之处在于无论Ca2+是否存在，δ亚基都能紧密结合在PhK中，作为其不可或缺的组成部分4,5。Ca2+可能通过与钙调蛋白结合产生的构象变化激活PhK。尽管关于PhK的研究已经持续近70年，但其具体的组装方式和激活的分子机理仍不完全清楚。2024年3月28日，北京大学生命科学学院肖俊宇课题组在Nature Communications期刊发表题为“Architecture and activation of human muscle phosphorylase kinase”的论文，揭示了PhK全酶的组装和激酶活性自抑制机制，并提出了PhK的Ca2+激活模型。
[前沿资讯 ] 非模块化脂肪酸合酶参与生成新型核糖体肽类天然产物 进入全文
科学网
核糖体肽类天然产物（RiPPs）是天然来源的具有丰富化学结构和生物活性的多肽化合物。目前，融合多种天然产物合成机制的RiPPs生物合成途径还鲜有报道。美国伊利诺伊大学香槟分校的赵惠民教授团队从自然界中发现并鉴定了一类兼具RiPPs和脂肪酸合成机制的杂合生物合成途径，可生成具有特殊脂酰基修饰的环状多肽lipoavitides，并发现了具有良好底物适应性、可作为多肽化合物改造潜在工具的酰基转移酶。相关成果“Non-modular fatty acid synthases yield distinct N-terminal acylation in ribosomal peptides”发表在2024年3月25日的Nature Chemistry期刊上。
[前沿资讯 ] 中国科学院微生物所在真菌混源萜生物合成机制研究中取得进展 进入全文
中国科学院微生物研究所
中国科学院微生物研究所刘钢研究团队与中国医学科学院药用植物研究所马国需团队合作在Journal of the American Chemical Society上发表论文，题为Two Cytochrome P450 Enzymes Form the Tricyclic Nested Skeleton of Meroterpenoids by Sequential Oxidative Reactions。该研究解析了大型真菌来源的混源萜clavilactone A的生物合成途径以及环化机制，有助于实现其高效精准制备。 Clavilactones是分离自大型真菌棒柄杯伞（Clitocybe clavipes）的一类莽草酸途径来源的混源萜，表现出良好的酪氨酸激酶抑制活性，具有开发成为抗肿瘤药物的潜力，但其生物合成途径和机制尚未被解析。 在前期工作基础上（ACS Catal. 2023, 13, 20, 13717–13728），该研究进一步阐明了clavilactones生物合成基因簇中的两个P450酶ClaR和ClaT的功能，完整解析了clavilactone A的生物合成途径和环化机制。其中P450酶ClaR通过催化底物geranylhydroquinone分子内对苯二酚及烯丙基的双自由基结合反应形成新颖的苯并十元碳环wigandol，接着多功能的P450酶ClaT催化十电子氧化反应，立体选择性的合成α，β-环氧-γ-内酯结构单元，完成clavilactone A中10/5/3三环嵌套结构的合成。该研究首次报道了P450酶在混源萜生物合成初期参与核心骨架的环化合成，扩展了P450酶的催化功能，为真菌来源的含有苯并大环的混源萜化合物的挖掘和生物合成解析奠定基础。
[学术文献 ] Gut-Derived Exosomes Mediate the Microbiota Dysbiosis-Induced Spermatogenesis Impairment by Targeting Meioc in Mice 进入全文
Advanced Science
iseases like obesity and intestinal inflammation diseases are accompanied by dysbiosis of the gut microbiota (DSGM), which leads to various complications, including systemic metabolic disorders. DSGM reportedly impairs the fertility of male mice; however, the regulatory mechanism is unclear. Exosomes are molecular mediators of intercellular communication, but the regulation of spermatogenesis by non-reproductive tissue-originated exosomes remains unknown. The present study shows that DSGM altered the miRNA expression profile of mouse circulating exosomes and impaired spermatogenesis. Moreover, the single-cell sequencing results indicate that circulating exosomes from mice with DSGM impaired spermatogenesis, while circulating exosomes from wild mice improved spermatogenesis by promoting meiosis. Further study demonstrates that DSGM leads to abnormal upregulation of miR-211-5p in gut-derived circulating exosomes, which inhibited the expression of meiosis-specific with coiled-coil domain (Meioc) in the testes and impaired spermatogenesis by disturbing meiosis process. In summary, this study defines the important role of gut-derived exosomes in connecting the "gut-testis" axis. This study proposes a new concept of the gut exosome testis axis. Following dysbiosis of gut microbiota, miR-211-5p loaded in the gut-derived circulating exosomes is increased abnormally and transported to the testicular seminiferous tubules through the blood circulation, targeting and inhibiting the expression of Meioc, consequently disturbing the meiosis process and impairing spermatogenesis.
[学术文献 ] Combinatorial High-Throughput Screening of Complex Polymeric Enzyme Immobilization Supports 进入全文
Journal of the American Chemical Society
Recent advances have demonstrated the promise of complex multicomponent polymeric supports to enable supra-biological enzyme performance. However, the discovery of such supports has been limited by time-consuming, low-throughput synthesis and screening. Here, we describe a novel combinatorial and high-throughput platform that enables rapid screening of complex and heterogeneous copolymer brushes as enzyme immobilization supports, named combinatorial high-throughput enzyme support screening (CHESS). Using a 384-well plate format, we synthesized arrays of three-component polymer brushes in the microwells using photoactivated surface-initiated polymerization and immobilized enzymes in situ. The utility of CHESS to identify optimal immobilization supports under thermally and chemically denaturing conditions was demonstrated usingBacillus subtilisLipase A (LipA). The identification of supports with optimal compositions was validated by immobilizing LipA on polymer-brush-modified biocatalyst particles. We further demonstrated that CHESS could be used to predict the optimal composition of polymer brushes a priori for the previously unexplored enzyme, alkaline phosphatase (AlkP). Our findings demonstrate that CHESS represents a predictable and reliable platform for dramatically accelerating the search of chemical compositions for immobilization supports and further facilitates the discovery of biocompatible and stabilizing materials.
[学术文献 ] Design of a Genetically Encoded Biosensor for High-Throughput Screening and Engineering 5-Aminolevulinic Acid Hyper-Producing Escherichia coli 进入全文
ACS Sustainable Chemistry & Engineering
5-Aminolevulinic acid (ALA) is a multifunctional nonprotein amino acid used in agriculture, medicine, and other fields. As current environmental problems become increasingly serious, it is of great significance to establish a cheap, environmentally friendly, and sustainable way to synthesize ALA. Therefore, the biosynthesis of ALA is receiving increasing attention. However, the lack of high-throughput screening methods for ALA has become a limiting factor in improving microbial production of ALA. In this study, a high-throughput screening method was developed based on the relationship between reactive oxygen species (ROS) caused by ALA and cyclic adenosine monophosphate (cAMP). First, the relationship between the ROS accumulation and changes in cAMP levels was verified. Subsequently, the selected promoter was optimized by adding cAMP receptor protein (CRP) binding sites at its upstream, and a high-throughput screening method for ALA was established. HemA mutant and ALA-producing Escherichia coli strain mutant were obtained and combined with a series of metabolic engineering strategies to improve ALA production. Finally, the ALA fed-batch fermentation in a 5 L fermenter achieved the highest ALA titer of 58.54 g/L with a productivity of 1.58 g/L/h. This laid the foundation for the industrialization of ALA through biosynthesis.
