Cytoplasmic residues of phospholamban interact with membrane surfaces in the presence of SERCA: A new role for phospholipids in the regulation of cardiac calcium cycling?
Cytoplasmic residues of phospholamban interact with membrane surfaces in the presence of SERCA: A new role for phospholipids in the regulation of cardiac calcium cycling?
复制标题
DOI：
10.1016/j.bbamem.2008.10.029
复制
发表时间：
2009-02-01
影响因子：
3.4
通讯作者：
Middleton, David A.
中科院分区：
文献类型：
--
作者：
Hughes, Eleri;Clayton, Jonathan C.;Middleton, David A.
2氨基酸跨膜蛋白磷蛋白（PLB）通过与肌浆网钙atp酶（SERCA）形成复合物并可逆地降低肌浆网钙摄取速率来调节心肌细胞中的钙循环。PLB的n端胞质结构域与SERCA的胞质结构域相互作用，但在缺乏该酶的情况下，也可以与阴离子磷脂膜表面结合。这项工作研究了在SERCA存在的情况下，PLB的细胞质结构域是否也可以与膜表面结合，以及这种相互作用是否会影响酶的调节。使用固态核磁共振和等温滴定量热法（ITC）表明，代表PLB的前23个n端氨基酸的n端乙酰化肽（PLB1-23）在没有和存在SERCA的情况下与两性离子磷脂酰胆碱（PC）和阴离子磷脂酰甘油（PC）脂质组成的膜相互作用。对肌浆网（SR）囊泡、平面SR膜和重组成PC/PG膜中SERCA的功能测量表明，PLB1-23通过作用于酶的细胞质面来降低ATP水解的最大速率。与单独在PC膜中的SERCA相比，在PC/PG膜中重组SERCA的肽抑制作用略有下降，但具有统计学意义。这表明，PLB细胞质结构域与带负电荷的磷脂之间的相互作用可能在调节SERCA的调节中发挥作用，从而影响心肌收缩性。(C) 2008 Elsevier B.V.版权所有
The 2-amino acid transmembrane protein phospholamban (PLB) regulates calcium cycling in cardiac cells by forming a complex with the sarco(endo)plasmic reticulum calcium ATPase (SERCA) and reversibly diminishing the rate of calcium uptake by the sarcoplasmic reticulum. The N-terminal cytoplasmic domain of PLB interacts with the cytoplasmic domain of SERCA, but, in the absence of the enzyme, can also associate with the surface of anionic phospholipid membranes. This work investigates whether the cytoplasmic domain of PLB can also associate with membrane surfaces in the presence of SERCA, and whether such interactions could influence the regulation of the enzyme. It is shown using solid-state NMR and isothermal titration calorimetry (ITC) that an N-terminally acetylated peptide representing the first 23 N-terminal amino acids of PLB (PLB1-23) interacts with membranes composed of zwitterionic phosphatidylcholine (PC) and anionic phosphatidylglycerol (PC) lipids in the absence and presence of SERCA. Functional measurements of SERCA in sarcoplasmic reticulum (SR) vesicles, planar SR membranes and reconstituted into PC/PG membranes indicate that PLB1-23 lowers the maximal rate of ATP hydrolysis by acting at the cytoplasmic face of the enzyme. A small, but statistically significant, reduction in the inhibitory effect of the peptide is observed for SERCA reconstituted into PC/PG membranes compared to SERCA in membranes of PC alone. It is suggested that interactions between the cytoplasmic domain of PLB and negatively charged phospholipids might play a role in moderating the regulation of SERCA, with implications for cardiac muscle contractility. (C) 2008 Elsevier B.V. All rights reserved.