2018 Fiscal Year Final Research Report
Structural basis for the regulation mechanism of intracellular polyamine concentration
| Project/Area Number |
16K07270
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Structural biochemistry
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| Research Institution | Kochi University (2017-2018)
Osaka University (2016) |
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Principal Investigator |
Sugiyama Shigeru 高知大学, 教育研究部自然科学系理工学部門, 教授 (90615428)
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| Research Collaborator |
IGARASHI Kazuei
KASHIWAGI Keiko
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Keywords | ポリアミン / 細胞増殖因子 / 生理活性物質 / アセチル転移酵素 / X線結晶構造解析 |
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| Outline of Final Research Achievements |
Polyamines such as spermidine (SPD) are distributed widely from prokaryotic to eukaryotic cells and are essential for cell growth. SPD acetyltransferase (SAT) from E. coli, which catalyses the transfer of acetyl groups from acetyl-CoA to spermidine, is a key enzyme in controlling polyamine levels in prokaryotic cells. In this study, we determined the crystal structure of SAT in complex with SPD and CoA at 2.5A resolution. SAT is a dodecamer organized as a hexamer of dimers. The SPD molecule is located at the inter-dimer interface. The distance between SPD and CoA molecules is 13A deep, highly acidic, water-filled cavity encompasses the SPD and CoA binding sites. Structure-based mutagenesis and in-vitro assays identified SPD-bound residues, and the acidic residues lining the walls of the cavity are mostly essential for enzymatic activities. Based on mutagenesis and structural data, we propose an acetylation mechanism underlying promiscuous polyamine recognition for SAT.
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| Free Research Field |
構造生物化学、タンパク質結晶学
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| Academic Significance and Societal Importance of the Research Achievements |
大腸菌ではポリアミン（PA）の生合成、分解、輸送に関わる遺伝子は、全体の実に0.6%も占めています。このことは、生体内でのPA制御機構が崩れると生命活動に影響を及ぼすことからも分かるように、生体内でのPA濃度の制御が非常に重要であると言えます。このように重要な機能を持つPAの細胞内濃度調節機構について構造生物学的な観点から研究を進めています。PA濃度はアセチル転移酵素（SAT）によって一部制御されています。SATは、病原性の赤痢菌や大腸菌の生存能力に重要な役割を持っています。本研究では、SATの立体構造を明らかにすることによりPAアセチル化転移反応機構を解明しました。
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