記述言語：英語   掲載種別：研究論文（学術雑誌）  

Bread dough is rich in polysaccharides and polyphenols, which hinder RNA extraction. We therefore established a streamlined workflow combining Fruit-mate homogenization, clarification, TRIzol extraction, high-salt precipitation, and activated-charcoal cleanup. This protocol reproducibly yields intact RNA of sufficient purity, enabling transcriptomic analyses of yeast activity in complex dough environments.

DOI： 10.1016/j.mimet.2025.107352

掲載種別：研究論文（学術雑誌）  

DOI： 10.1093/femsyr/foaf065

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Humans and mammals need to ingest essential amino acids (EAAs) for protein synthesis. In addition to their importance as nutrients, EAAs are involved in brain homeostasis. However, elderly people are unable to efficiently consume EAAs from their daily diet due to reduced appetite and variations in the contents of EAAs in foods. On the other hand, strains of the yeast Saccharomyces cerevisiae that accumulate EAAs would enable elderly people to intakegest adequate amounts of EAAs and thus might slow down the neurodegenerative process, contributing to the extension of their healthy lifespan. In this study, we isolated a mutant (strain HNV-5) that accumulates threonine, an EAA, derived from a diploid laboratory yeast by conventional mutagenesis. Strain HNV-5 carries a novel mutation in the HOM3 gene encoding the Ala462Thr variant of aspartate kinase (AK). Enzymatic analysis revealed that the Ala462Thr substitution significantly decreased the sensitivity of AK activity to threonine feedback inhibition even in the presence of 50 mM threonine. Interestingly, Ala462Thr substitution did not affect the catalytic ability of Hom3, in contrast to previously reported amino acid substitutions that resulted in reduced sensitivity to threonine feedback inhibition. Furthermore, yeast cells expressing the Ala462Thr variant showed an approximately threefold increase in intracellular threonine content compared to that of the wild-type Hom3. These findings will be useful for the development of threonine-accumulating yeast strains that may improve the quality of life in elderly people.IMPORTANCEFor humans and mammals, essential amino acids (EAAs) play an important role in maintaining brain function. Therefore, increasing the intake of EAAs by using strains of the yeast Saccharomyces cerevisiae that accumulate EAAs may inhibit neurodegeneration in elderly people and thus contribute to extending healthy lifespan and improving their quality of life. Threonine, an EAA, is synthesized from aspartate. Aspartate kinase (AK) catalyzes the first step in threonine biosynthesis and is subject to allosteric regulation by threonine. Here, we isolated a threonine-accumulating mutant of S. cerevisiae by conventional mutagenesis and identified a mutant gene encoding a novel variant of AK. In contrast to previously isolated variants, the Hom3 variant exhibited AK activity that was insensitive to feedback inhibition by threonine but retained its catalytic ability. This resulted in increased production of threonine in yeast. These findings open up the possibility for the rational design of AK to increase threonine productivity in yeast.

DOI： 10.1128/aem.00155-24

掲載種別：研究論文（学術雑誌）  

DOI： 10.1093/BBB/ZBAE154

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1093/femsyr/foad012

会議種別：口頭発表（一般）  

開催年月日： 2019年9月

記述言語：日本語   会議種別：口頭発表（一般）  

会議種別：口頭発表（一般）  

会議種別：口頭発表（一般）  

記述言語：日本語   会議種別：口頭発表（一般）  

受賞区分：国内学会・会議・シンポジウム等の賞  受賞国：日本国