Paoletti F, Konarev P V, Covaceuszach S, Schwarz E, Cattaneo A, Lamba D, Svergun D I
SISSA/ISAS (Scuola Internazionale Superiore di Studi Avanzati/International School of Advanced Studies), Trieste, Italy.
Biochem Soc Trans. 2006 Aug;34(Pt 4):605-6. doi: 10.1042/BST0340605.
The unprocessed pro-form of the NGF (nerve growth factor), proNGF (NGF precursor, without signal peptide), has been suggested to have additional functions distinct from its role as a promoter of protein folding, i.e. apoptosis and/or neurotrophic activity. Aiming to gain insights into the specific molecular interactions that mediate proNGF biological activity and into the structural determinants stabilizing its pro-region, rm-proNGF (recombinant mouse proNGF) was expressed in Escherichia coli, refolded in vitro and characterized by physicochemical methods. X-ray solution scattering measurements (small angle X-ray scattering) revealed that rm-proNGF is dimeric in solution and appears to be anisometric when compared with the compact structure of the NGF dimer. Two structural models, a globular crab-like shape and an elongated rod-like shape, equally fit to the experimental results, pointing to an intrinsically structural disordered pro-region of NGF. The models obtained allowed the interpretation of TrkA (tropomyosin receptor kinase A) binding and activation assays in cell cultures, shedding new light on the key role of proNGF in neuronal survival and neurodegeneration.
神经生长因子（NGF）的未加工前体形式，即proNGF（NGF前体，无信号肽），被认为具有不同于其作为蛋白质折叠促进剂的其他功能，即凋亡和/或神经营养活性。为了深入了解介导proNGF生物活性的特定分子相互作用以及稳定其前区的结构决定因素，重组小鼠proNGF（rm-proNGF）在大肠杆菌中表达，体外重折叠并通过物理化学方法进行表征。X射线溶液散射测量（小角X射线散射）表明，rm-proNGF在溶液中是二聚体，与NGF二聚体的紧密结构相比似乎是不等轴的。两种结构模型，一种球状蟹状形状和一种细长棒状形状，同样符合实验结果，表明NGF的前区具有内在结构无序性。所获得的模型有助于解释细胞培养中的TrkA（原肌球蛋白受体激酶A）结合和激活试验，为proNGF在神经元存活和神经退行性变中的关键作用提供了新的线索。
