Laboratory of Biological Physics, Institute of Physics, Polish Academy of Sciences, Warsaw, Poland.
Biophys Chem. 2011 Oct;158(2-3):141-9. doi: 10.1016/j.bpc.2011.06.010. Epub 2011 Jun 24.
Deadenylation is the initial and often rate-limiting step in the main pathways of eukaryotic mRNA decay. Poly(A)-specific ribonuclease (PARN) is a eukaryotic enzyme that efficiently degrades mRNA poly(A) tails. Structural and functional studies have shown that human PARN is composed of at least three functional domains, i.e. the catalytic nuclease domain and two RNA binding domains, the R3H and the RNA recognition motif (RRM), respectively. However, the complete structure of the full length protein is still unknown. We have investigated the global architecture of human PARN by atomic force microscopy (AFM) imaging in buffered milieu and report for the first time the dimensions of the full length protein at subnanometer resolution. The AFM images of single PARN molecules reveal compact ellipsoidal dimers (10.9 × 7.6 × 4.6nm). The dimeric form of PARN was confirmed by dynamic light scattering (DLS) measurements that rendered a molecular weight of 161 kDa, in accordance with previous crystal structures of PARN fragments showing a dimeric composition. We discuss a putative internal arrangement of three functional domains within the full length PARN dimer.
脱腺苷酸化是真核生物 mRNA 降解主要途径中的初始步骤，也是限速步骤。聚腺苷酸特异性核糖核酸酶 (PARN) 是一种能有效降解 mRNA 聚腺苷酸尾的真核酶。结构和功能研究表明，人类 PARN 至少由三个功能域组成，即催化核酶域和两个 RNA 结合域，R3H 和 RNA 识别基序 (RRM)。然而，全长蛋白的完整结构仍不清楚。我们通过原子力显微镜 (AFM) 在缓冲介质中的成像研究了人类 PARN 的整体结构，并首次在亚纳米分辨率下报告了全长蛋白的尺寸。单个 PARN 分子的 AFM 图像显示出紧凑的椭圆形二聚体（10.9×7.6×4.6nm）。PARN 的二聚体形式通过动态光散射 (DLS) 测量得到证实，分子量为 161 kDa，与以前显示二聚体组成的 PARN 片段的晶体结构一致。我们讨论了全长 PARN 二聚体内三个功能域的内部排列。
