Iyer Prabha P, Lawrence Sarah H, Yennawar Hemant P, Ferry James G
Department of Biochemistry and Molecular Biology, The Pennsylvania State University, USA.
Acta Crystallogr D Biol Crystallogr. 2003 Aug;59(Pt 8):1517-20. doi: 10.1107/s0907444903013428. Epub 2003 Jul 23.
Phosphotransacetylase (Pta) from the anaerobic archaeon Methanosarcina thermophila has been heterologously expressed in a soluble form which facilitated crystallization using the hanging-drop vapor-diffusion method with ammonium sulfate as a precipitant. This is the first report of the crystallization of any Pta. While the M. thermophila Pta has high sequence identity to Ptas from other organisms, it has no homology to any previously crystallized proteins. The protein crystallized in space group I4(1), with unit-cell parameters a = b = 114.8, c = 127.8 A, alpha = beta = gamma = 90 degrees. The crystals diffracted to 2.5 A resolution using Cu Kalpha radiation. The enzyme had previously been reported to exist as a monomer; however, the self-rotation function showed the presence of a non-crystallographic symmetry axis at psi = 90, phi = 90, kappa = 180 degrees, suggesting oligomerization. Dynamic light-scattering analysis supported a dimeric state for Pta in solution.
嗜热甲烷八叠球菌的磷酸转乙酰酶（Pta）已以可溶形式异源表达，这有助于使用硫酸铵作为沉淀剂的悬滴气相扩散法进行结晶。这是关于任何Pta结晶的首次报道。虽然嗜热甲烷八叠球菌的Pta与其他生物体的Pta具有高度的序列同一性，但它与任何先前结晶的蛋白质都没有同源性。该蛋白质在空间群I4(1)中结晶，晶胞参数为a = b = 114.8，c = 127.8 Å，α = β = γ = 90°。使用Cu Kα辐射时，晶体衍射至2.5 Å分辨率。此前报道该酶以单体形式存在；然而，自旋转函数显示在ψ = 90、φ = 90、κ = 180°处存在非晶体学对称轴，表明存在寡聚化。动态光散射分析支持溶液中的Pta处于二聚体状态。
