Role of Acyl Chain Composition of Phosphatidylcholine in Tafazzin-Mediated Remodeling of Cardiolipin in Liposomes
作者:Masato Abe、Yoshiki Sawada、Shinpei Uno、Shuhei Chigasaki、Masahide Oku、Yasuyoshi Sakai、Hideto Miyoshi
DOI:10.1021/acs.biochem.7b00941
日期:2017.11.28
Remodeling of the acyl chain compositions of cardiolipin (CL) species by the transacylase tafazzin is an important process for maintaining optimal mitochondrial functions. The results of mechanistic studies on the tafazzin-mediated transacylation from phosphatidylcholine (PC) to monolyso-CL (MLCL) in artificial lipid membranes are controversial. The present study investigated the role of the acyl chain composition of PC in the Saccharomyces cerevisiae tafazzin-mediated remodeling of CL by examining the structural factors responsible for the superior acyl donor ability of dipalmitoleoyl (16:1) PC over dipalmitoyl (16:0) PC. To this end, we synthesized systematic derivatives of dipalmitoleoyl PC; for example, the location of the cis double bond was migrated from the Δ9-position toward either end of the acyl chains (the Δ5- or Δ13-position), the cis double bond in the sn-1 or sn-2 position or both, was changed to a trans form, and palmitoleoyl and palmitoyl groups were exchanged in the sn-1 and sn-2 positions, maintaining similar PC fluidities. Analyses of the tafazzin-mediated transacylation from these PCs to sn-2′-MLCL(18:1-18:1/18:1-OH) in the liposomal membrane revealed that tafazzin strictly discriminates the molecular configuration of the acyl chains of PCs, including their glycerol positions (sn-1 or sn-2); however, the effects of PC fluidity on the reaction may not be neglected. On the basis of the findings described herein, we discuss the relevance of the so-called thermodynamic remodeling hypothesis that presumes no acyl selectivity of tafazzin.
通过转酰基酶塔法津重塑心磷脂(CL)的酰基链组成是维持线粒体最佳功能的重要过程。关于人工脂质膜中塔法津介导的磷脂酰胆碱(PC)向单溶酶-CL(MLCL)转酰基化的机理研究结果存在争议。本研究通过检测双棕榈酰(16:1)PC比双棕榈酰(16:0)PC具有更优越的酰基供体能力的结构因素,研究了PC的酰基链组成在酿酒酵母塔法津介导的CL重塑中的作用。为此,我们合成了双棕榈酰PC的系统衍生物;例如,顺式双键的位置从Δ9位向酰基链的两端(Δ5位或Δ13位)移动,sn-1或sn-2位或两者的顺式双键变为反式,并在sn-1和sn-2位交换棕榈酰基和棕榈酰基,以保持相似的PC流动性。对脂质体膜中塔法津介导的从这些PC向sn-2′-MLCL(18:1-18:1/18:1-OH)的转酰基化分析表明,塔法津严格区分PC的酰基链的分子构型,包括其甘油位置(sn-