Metabolic Engineering Group, Departamento de Microbiología y Genética, Universidad de Salamanca, Edificio Departamental, Campus Miguel de Unamuno, 37007, Salamanca, Spain.
Department Abiotic Stress, Instituto de Recursos Naturales y Agrobiología, Consejo Superior de Investigaciones Científicas, C/ Cordel de Merinas 40-52, 37008, Salamanca, Spain.
Appl Microbiol Biotechnol. 2015 Nov;99(22):9577-89. doi: 10.1007/s00253-015-6710-2. Epub 2015 Jul 7.
Guanine nucleotides are the precursors of essential biomolecules including nucleic acids and vitamins such as riboflavin. The enzyme inosine-5'-monophosphate dehydrogenase (IMPDH) catalyzes the ratelimiting step in the guanine nucleotide de novo biosynthetic pathway and plays a key role in controlling the cellular nucleotide pools. Thus, IMPDH is an important metabolic bottleneck in the guanine nucleotide synthesis, susceptible of manipulation by means of metabolic engineering approaches. Herein, we report the functional and structural characterization of the IMPDH enzyme from the industrial fungus Ashbya gossypii. Our data show that the overexpression of the IMPDH gene increases the metabolic flux through the guanine pathway and ultimately enhances 40 % riboflavin production with respect to the wild type. Also, IMPDH disruption results in a 100-fold increase of inosine excretion to the culture media. Our results contribute to the developing metabolic engineering toolbox aiming at improving the production of metabolites with biotechnological interest in A. gossypii.
鸟嘌呤核苷酸是包括核酸和维生素（如核黄素）在内的重要生物分子的前体。肌苷-5'-单磷酸脱氢酶（IMPDH）催化鸟嘌呤核苷酸从头生物合成途径中的限速步骤，在控制细胞核苷酸池方面发挥着关键作用。因此，IMPDH 是鸟嘌呤核苷酸合成中的一个重要代谢瓶颈，可通过代谢工程方法进行操作。本文报告了工业真菌棉铃霉菌（Ashbya gossypii）IMPDH 酶的功能和结构特征。我们的数据表明，IMPDH 基因的过表达增加了通过鸟嘌呤途径的代谢通量，最终使相对于野生型的核黄素产量提高了 40%。此外，IMPDH 缺失会导致肌苷向培养基中的排泄增加 100 倍。我们的研究结果为正在开发的代谢工程工具包做出了贡献，旨在提高棉铃霉菌中具有生物技术意义的代谢物的产量。
