Mandel Corey R, Gebauer Damara, Zhang Hailong, Tong Liang
Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
Acta Crystallogr Sect F Struct Biol Cryst Commun. 2006 Oct 1;62(Pt 10):1041-5. doi: 10.1107/S1744309106038152. Epub 2006 Sep 30.
The cleavage and polyadenylation specificity factor (CPSF) complex is required for the cleavage and polyadenylation of the 3'-end of messenger RNA precursors in eukaryotes. During structural studies of the 100 kDa subunit (CPSF-100, Ydh1p) of the yeast CPSF complex, it was serendipitously discovered that a solution that is infected by a fungus (subsequently identified as Penicillium) is crucial for the crystallization of this protein. Further analyses suggest that the protein has undergone partial proteolysis during crystallization, resulting in the deletion of an internal segment of about 200 highly charged and hydrophilic residues, very likely catalyzed by a protease secreted by the fungus. With the removal of this segment, yeast CPSF-100 (Ydh1p) has greatly reduced solubility and can be crystallized in the presence of a minute amount of precipitant.
切割与聚腺苷酸化特异性因子（CPSF）复合物是真核生物中信使RNA前体3'末端切割与聚腺苷酸化所必需的。在对酵母CPSF复合物100 kDa亚基（CPSF - 100，Ydh1p）进行结构研究期间，意外发现被一种真菌（随后鉴定为青霉菌）污染的溶液对该蛋白质的结晶至关重要。进一步分析表明，该蛋白质在结晶过程中发生了部分蛋白水解，导致约200个高度带电且亲水性残基的内部片段缺失，很可能是由真菌分泌的蛋白酶催化的。随着该片段的去除，酵母CPSF - 100（Ydh1p）的溶解度大大降低，并且可以在存在微量沉淀剂的情况下结晶。
