Structural characterization of reaction pathway in a PLP-enzyme, methionine gamma-lyase: crystallographic snapshots of key intermediates

2014 Fiscal Year Final Research Report

• Project/Area Number: 23370050
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Structural biochemistry
• Research Institution: Kyoto Institute of Technology
• Principal Investigator: HARADA shigeharu 京都工芸繊維大学, 工芸科学研究科, 教授 (80156504)
• Project Period (FY): 2011-04-01 – 2015-03-31
• Keywords: 酵素反応機構 / 生体分子 / PLP酵素 / タンパク質 / 時分割X線解析 / スナップショット構造

Outline of Final Research Achievements

Pyridoxal 5'-phosphate (PLP) is an indispensable cofactor in many enzymes. The catalytic mechanism of the first part, from substrate binding to PLP to formation of quinonid intermediate, is characterized in several PLP enzymes, but the latter half is not fully understood. We determined X-ray structures of a series of reaction intermediates to elucidate the mechanism of PLP-dependent methionine γ-lyase. The structures reveal that the methionine degradation is carried out by aldimine-based C4'-Nα-Cα system, followed by proton migration from the Cα to C4' position. After releasing methanethiol, the latter half of intermediates suggest that the reaction processes leading to the releasing 2-aminobutyrate accounted for a concerted [1,5]-hydrogen sigmatropy with respect to the C4' and Cγ-carbon sites. Taken together, these structural intermediates successfully depicted overall reaction process of γ-elimination.

Free Research Field

構造生物学