Analysis of enlargement mechanism of substrate specificity of CTX-M type beta-lactamase based on protein crystallography.

2015 Fiscal Year Final Research Report

• Project/Area Number: 25670276
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Laboratory medicine
• Research Institution: Nara Medical University
• Principal Investigator: YAMAMOTO Keizo 奈良県立医科大学, 医学部, 准教授 (90254490)
• Co-Investigator(Kenkyū-buntansha): KASAHARA Kei 奈良県立医科大学, 医学部, 准教授 (50405403) ; NAKAYAMA Akifumi 岐阜医療科学大学, 保険科学部, 教授 (70536721)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: βーラクタマーゼ / X線結晶構造解析 / 基質特異性 / 構造変化

Outline of Final Research Achievements

Plasmid-mediated extended spectrum beta-lactamases (ESBLs) named CTX-M causes hospital- and community-acquired infections in Japan. Comparison of DNA sequences and structures of CTX-Ms showed that amino acid substitution in the three loop regions, omega-loop, VNYNP-loop, and a loop connecting alpha/beta domain mast be important to change of substrate specificity. Ala-219 which locates in a loop connecting alpha/beta domain is considered as a key residue to substrate specificity. Thus, the structures of three mutant enzymes, A219V, A219L, A219F, and wild type CTX-M-2 were solved. Although the structural difference among wild type, A219V, and A219F were very small, maximum XYZ-difference between wild type and A219L were 0.42 nm. It reveals that the structure of CTX-Ms is latently flexible and mutation in the loop region raises changes of overall structure and substrate specificity.

Free Research Field

タンパク質工学