Biochemical characterization of various catalytic complexes of the brain platelet-activating factor acetylhydrolase
Biochemical characterization of various catalytic complexes of the brain platelet-activating factor acetylhydrolase
复制标题
DOI：
10.1074/jbc.274.45.31827
复制
发表时间：
1999-11-05
影响因子：
4.8
通讯作者：
Inoue, K
中科院分区：
文献类型：
--
作者：
Manya, H;Aoki, J;Inoue, K
脑细胞内血小板活化因子乙酰水解酶(PAF-AH)亚型I是由相互同源的催化活性的α(1)和α(2)亚基和β亚基组成的复合酶家族的成员。我们先前证明了一个催化亚基α(1)的表达是发育调节的，导致在脑发育过程中催化复合体从α(1)/α(2)切换到α(2)/α(2)(Manya，H.，Aoki，J.，Watanabe，M.，Adachi，T.，Asou，H.，Inoue，Y.，Arai，H.和Inoue，K.(1998)J.Biol)。化学。273、18567-18572)。在这项研究中，我们探索了三种可能的催化二聚体，α(1)/α(1)，α(1)/α(2)和α(2)/α(2)的生化差异。α(2)/α(2)同源二聚体表现出不同于α(1)/α(1)同源二聚体和α(1)/α(2)杂二聚体的底物专一性，两者具有相似的底物专一性。在1-O-烷基-2-乙酰基磷脂中，α(2)/α(2)均二聚体对PAF和1-O-alkyl-2-acetyl-sn-glycero-3-phosphorylethanolamine的水解率最高。相反，α(1)/α(1)和α(1)/α(2)对1-O-烷基-2-乙酰基-sn-甘油-3-磷酸的水解率均高于PAF。AAGPE是这些酶的最差底物。β亚基与所有三个催化二聚体结合，但以催化二聚体组成依赖的方式调节酶活性。β亚基强烈促进α(2)/α(2)同源二聚体的酶活性，抑制α(1)/α(1)同源二聚体的活性，而对α(1)/α(2)异二聚体的影响不大。最近在孤立的无脑畸形患者中发现的(His(149)to Arg)突变β失去了与催化复合体结合或调节其酶活性的能力。PAF-AH异构体I的酶活性可通过改变催化亚基的组成和操纵β亚基以多种方式调节。
Brain intracellular platelet-activating factor acetylhydrolase (PAF-AH) isoform I is a member of a family of complex enzymes composed of mutually homologous alpha(1) and alpha(2) subunits, both of which account for catalytic activity, and the beta subunit. We previously demonstrated that the expression of one catalytic subunit, alpha(1), is developmentally regulated, resulting in a switching of the catalytic complex from alpha(1)/alpha(2) to alpha(2)/alpha(2) during brain development (Manya, H., Aoki, J., Watanabe, M., Adachi, T., Asou, H., Inoue, Y., Arai, H., and Inoue, K. (1998) J. Biol. Chem. 273, 18567-18572). In this study, we explored the biochemical differences in three possible catalytic dimers, alpha(1)/alpha(1), alpha(1)/alpha(2), and alpha(2)/alpha(2). The alpha(2)/alpha(2) homodimer exhibited different substrate specificity from the alpha(1)/alpha(1) homodimer and the alpha(1)/alpha(2) heterodimer, both of which showed similar substrate specificity. The alpha(2)/alpha(2) homodimer hydrolyzed PAF and 1-O-alkyl-2-acetyl-sn-glycero-3-phosphorylethanolamine (AAGPE) most efficiently among 1-O-alkyl-2-acetyl-phospholipids. In contrast, both alpha(1)/alpha(1) and alpha(1)/alpha(2) hydrolyzed 1-O-alkyl-2-acetyl-sn-glycero-3-phosphoric acid more efficiently than PAF. AAGPE was the poorest substrate for these enzymes. The beta subunit bound to all three catalytic dimers but modulated the enzyme activity in a catalytic dimer composition-dependent manner. The beta subunit strongly accelerated the enzyme activity of the alpha(2)/alpha(2) homodimer but rather suppressed the activity of the alpha(1)/alpha(1) homodimer and had little effect on that of the alpha(1)/alpha(2) heterodimer. The (His(149) to Arg) mutant beta, which has been recently identified in isolated lissencephaly sequence patients, lost the ability to either associate with the catalytic complexes or modulate their enzyme activity. The enzyme activity of PAF-AH isoform I may be regulated in multiple ways by switching the composition of the catalytic subunit and by manipulating the beta subunit.