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首页> 外文期刊>Biochemistry >Phosphatidylethanolamine modulates Ca-ATPase function and dynamics.
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Phosphatidylethanolamine modulates Ca-ATPase function and dynamics.

机译：磷脂酰乙醇胺调节Ca-ATPase的功能和动力学。

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摘要

Phospholipids containing phosphoethanolamine (PE) headgroups within biological membranes have been suggested to be important with respect to the functional regulation of membrane proteins, including the Ca-ATPase in sarcoplasmic reticulum (SR). To investigate the role of PE headgroups in modulating the catalytic activity of the Ca-ATPase, we have reconstituted the Ca-ATPase into unilamellar liposomes containing defined amounts of dioleoylphosphatidylethanolamine (DOPE) and dioleoylphosphatidylcholine (DOPC). The enzymatic activity of the Ca-ATPase progressively increases upon incorporation of increasing amounts of PE into reconstituted vesicles, and approaches that characteristic of native SR membranes. To identify structural changes that correlate with enzyme activation, we have used frequency-domain phosphorescence spectroscopy to measure the rotational dynamics of erythrosin isothiocyanate covalently bound to Lys464 in the phosphorylation domain of the Ca-ATPase. Progressive increases in the rotational dynamics of the phosphorylation domain result from the incorporation of increasing amounts of DOPE, and correlate with enhanced enzymatic function. These results suggest that PE headgroups induce dynamic structural rearrangements involving the phosphorylation domain that modify the rates of nucleotide utilization. In contrast, no changes in the rotational dynamics of the lipid acyl chains are observed irrespective of the PE content. Therefore, the enhanced ATP hydrolytic activity associated with the incorporation of DOPE into these proteoliposomes is the result of specific noncovalent interactions involving PE phospholipid headgroups and the Ca-ATPase.
机译：已经有人提出，在生物膜中含有磷酸乙醇胺（PE）头基的磷脂对于膜蛋白（包括肌浆网（SR）中的Ca-ATPase）的功能调节很重要。为了研究PE头基在调节Ca-ATPase催化活性中的作用，我们将Ca-ATPase重构为单层脂质体，其中含有确定量的二油酰基磷脂酰乙醇胺（DOPE）和二油酰基磷脂酰胆碱（DOPC）。当将越来越多的PE掺入到重构的囊泡中时，Ca-ATPase的酶活性逐渐增加，并接近天然SR膜的特征。为了确定与酶激活相关的结构变化，我们使用了频域磷光光谱法来测量在Ca-ATPase磷酸化域中共价结合Lys464的赤藓红异硫氰酸酯的旋转动力学。磷酸化域的旋转动力学的逐步增加是由于掺入了增加量的DOPE所致，并且与增强的酶功能相关。这些结果表明，PE头基会诱导涉及磷酸化结构域的动态结构重排，从而改变核苷酸利用率。相反，无论PE含量如何，都没有观察到脂酰基链旋转动力学的变化。因此，与DOPE掺入这些蛋白脂质体相关的增强的ATP水解活性是涉及PE磷脂头基和Ca-ATPase的特定非共价相互作用的结果。

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