Dunten P, Kammlott U, Crowther R, Weber D, Palermo R, Birktoft J
Roche Research Center, Hoffmann-La Roche Inc., Nutley, New Jersey 07110, USA.
Biochemistry. 1998 Jun 2;37(22):7907-12. doi: 10.1021/bi980531o.
The rat protein farnesyltransferase crystal structure has been solved by multiple isomorphous replacement methods at a resolution of 2.75 A. The three-dimensional structure, together with recent data on the effects of several mutations, led us to propose a model for substrate binding which differs from the model presented by Park et al. based on their independent structure determination [Park, H. -W., Boduluri, S. R., Moomaw, J. F., Casey, P. J., and Beese, L. S. (1997) Science 275, 1800-1804]. Both farnesyl diphosphate and peptide substrates can be accommodated in the hydrophobic active-site barrel, with the sole charged residue inside the barrel, Arg202 of the beta-subunit, forming a salt bridge with the negatively charged carboxy terminus of peptide substrates. Our proposals are based in part on the observation of electron density in the active site which can be modeled as bound farnesyl diphosphate carried through the enzyme purification. In addition, our model explains in structural terms the results of mutational studies which have identified several residues critical for substrate specificity and catalysis.
大鼠蛋白质法尼基转移酶的晶体结构已通过多同晶置换法解析，分辨率为2.75埃。三维结构以及最近关于几种突变效应的数据，使我们提出了一种底物结合模型，该模型与Park等人基于他们独立的结构测定所提出的模型不同[Park, H. -W., Boduluri, S. R., Moomaw, J. F., Casey, P. J., and Beese, L. S. (1997) Science 275, 1800 - 1804]。法尼基二磷酸和肽底物都可以容纳在疏水的活性位点桶中，桶内唯一的带电荷残基，即β亚基的Arg20二磷酸和肽底物都可以容纳在疏水的活性位点桶中，桶内唯一的带电荷残基，即β亚基的Arg202，与肽底物带负电荷的羧基末端形成盐桥。我们的提议部分基于对活性位点电子密度的观察，该电子密度可以模拟为在酶纯化过程中携带的结合法尼基二磷酸。此外，我们的模型从结构角度解释了突变研究的结果，这些研究确定了几个对底物特异性和催化至关重要的残基。
