Chu Shidong, Coey Aaron T, Lorigan Gary A
Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA.
Biochim Biophys Acta. 2010 Feb;1798(2):210-5. doi: 10.1016/j.bbamem.2009.09.025. Epub 2009 Oct 17.
Phospholamban (PLB) is an integral membrane protein regulating Ca(2+) transport through inhibitory interaction with sarco(endo)plasmic reticulum calcium ATPase (SERCA). The Asn27 to Ala (N27A) mutation of PLB has been shown to function as a superinhibitor of the affinity of SERCA for Ca(2+) and of cardiac contractility in vivo. The effects of this N27A mutation on the side-chain and backbone dynamics of PLB were investigated with (2)H and (15)N solid-state NMR spectroscopy in phospholipid multilamellar vesicles (MLVs). (2)H and (15)N NMR spectra indicate that the N27A mutation does not significantly change the side-chain or backbone dynamics of the transmembrane and cytoplasmic domains when compared to wild-type PLB. However, dynamic changes are observed for the hinge region, in which greater mobility is observed for the CD(3)-labeled Ala24 N27A-PLB. The increased dynamics in the hinge region of PLB upon N27A mutation may allow the cytoplasmic helix to more easily interact with the Ca(2+)-ATPase; thus, showing increased inhibition of Ca(2+)-ATPase.
受磷蛋白（PLB）是一种整合膜蛋白，通过与肌浆网钙ATP酶（SERCA）的抑制性相互作用来调节Ca(2+)转运。已证明PLB的Asn27突变为Ala（N27A）在体内可作为SERCA对Ca(2+)亲和力和心脏收缩力的超抑制剂。利用(2)H和(15)N固态核磁共振光谱技术，在磷脂多层囊泡（MLV）中研究了这种N27A突变对PLB侧链和主链动力学的影响。(2)H和(15)N核磁共振光谱表明，与野生型PLB相比，N27A突变不会显著改变跨膜结构域和胞质结构域的侧链或主链动力学。然而，在铰链区观察到了动态变化，其中CD(3)标记的Ala24 N27A-PLB具有更高的流动性。N27A突变后PLB铰链区动力学的增加可能使胞质螺旋更容易与Ca(2+)-ATP酶相互作用；因此，显示出对Ca(2+)-ATP酶的抑制作用增强。
