The functional implications of the dimerization of the catalytic subunits of the mammalian brain platelet-activating factor acetylhydrolase (Ib)

T. W.P. McMullen, J. Li, P. J. Sheffield, J. Aoki, T. W. Martin, H. Arai, K. Inoue, Z. S. Derewenda

研究成果: Article査読

11 被引用数 (Scopus)

抄録

The mammalian brain contains significant amounts of the cytosolic isoform Ib of the platelet-activating factor acetylhydrolase (PAF-AH), a unique type of PLA2. This oligomeric protein complex contains three types of subunits: two homologous (63% identity) 26 kDa catalytic subunits (α1 and α2) which harbor all the PAF-AH activity, and the 45 kDa β-subunit (LIS1), a product of the causal gene for Miller-Dieker lissencephaly. During fetal development, the preferentially expressed α1-subunit forms a homodimer, which binds to a homodimer of LIS1, whereas in adult organisms α12 and α22 dimers, also bound to dimeric LIS1, are the prevailing species. The consequences of this 'switching' are not understood, but appear to be of physiological significance. The α1- and α2-subunits readily associate with very high affinity to form homodimers. The nature of the interface has been elucidated by the 1.7 Å resolution crystal structure of the α11 homodimer (Ho et al., 1997). Here, we examined the functional consequences of the dimerization in both types of α-subunits. We obtained monomeric protein in the presence of high concentrations (>50 mM) of Ca2+ ions, and we show that it is catalytically inactive and less stable than the wild type. We further show that Arg29 and Arg22 in one monomer contribute to the catalytic competence of the active site across the dimer interface, and complement the catalytic triad of Ser47, Asp192 and His195, in the second monomer. These results indicate that the brain PAF-acetylhydrolase is a unique PLA2 in which dimerization is essential for both stability and catalytic activity.

本文言語English
ページ(範囲)865-871
ページ数7
ジャーナルProtein Engineering
13
12
DOI
出版ステータスPublished - 2000

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology

フィンガープリント 「The functional implications of the dimerization of the catalytic subunits of the mammalian brain platelet-activating factor acetylhydrolase (Ib)」の研究トピックを掘り下げます。これらがまとまってユニークなフィンガープリントを構成します。

引用スタイル