Evolution of the immunoproteasome PSMB8 gene

2014 Fiscal Year Final Research Report

• Project/Area Number: 24370094
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Evolutionary biology
• Research Institution: The University of Tokyo
• Principal Investigator: NONAKA MASARU 東京大学, 理学(系)研究科(研究院), 教授 (40115259)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 進化 / 平衡選択 / プロテアソーム / 二型性 / 主要組織適合性抗原複合体

Outline of Final Research Achievements

The proteasome subunit beta type 8 gene (PSMB8) encodes one of the beta subunits of the immunoproteasome responsible for the generation of peptides presented MHC class I molecules. Phylogenetic analysis revealed the presence of dichotomous ancient lineages persisting more than 400 million years. To clarify the whole picture of evolution of the PSMB8 dimorphism, more than 10 species of teleost, amphibian and reptile were analyzed. Most of them seem to have lost one of the two lineages, and then have recovered dimorphism within the other lineage. However, this explanation is incompatible with the presence of a strong selective pressure to keep dimorphism, and interallelic sequence homogenization was proposed as a possible evolutionary mechanism for the apparent recurrent regeneration of PSMB8 dimorphism in these animals. An extremely strong balancing selection acting on PSMB8 dimorphism was implicated in an unprecedented pattern of allele evolution.

Free Research Field

進化免疫学