Kolev Nikolay G, Yario Therese A, Benson Eleni, Steitz Joan A
Howard Hughes Medical Institute, Yale University, 295 Congress Avenue, New Haven, Connecticut 06519, USA.
EMBO Rep. 2008 Oct;9(10):1013-8. doi: 10.1038/embor.2008.146. Epub 2008 Aug 8.
In eukaryotes, the process of messenger RNA 3'-end formation involves endonucleolytic cleavage of the transcript followed by synthesis of the poly(A) tail. The complex machinery involved in this maturation process contains two proteins of the metallo-beta-lactamase (MBL) superfamily, the 73 and 100 kDa subunits of the cleavage and polyadenylation specificity factor (CPSF). By using an in vitro system to assess point mutations in these two mammalian proteins, we found that conserved residues from the MBL motifs of both polypeptides are required for assembly of the endonuclease activity that cleaves histone pre-mRNAs. This indicates that CPSF73 and CPSF100 act together in the process of maturation of eukaryotic pre-messenger RNAs, similar to other members of the MBL family, RNases Z and J, which function as homodimers.
在真核生物中，信使核糖核酸（mRNA）3' 端形成过程涉及转录本的核酸内切酶切割，随后合成聚腺苷酸（poly(A)）尾。参与这一成熟过程的复杂机制包含金属β-内酰胺酶（MBL）超家族的两种蛋白质，即切割及聚腺苷酸化特异性因子（CPSF）的73 kDa和100 kDa亚基。通过使用体外系统评估这两种哺乳动物蛋白质中的点突变，我们发现这两种多肽的MBL基序中的保守残基是切割组蛋白前体mRNA的内切酶活性组装所必需的。这表明CPSF73和CPSF100在真核生物前体信使RNA的成熟过程中共同发挥作用，类似于MBL家族的其他成员核糖核酸酶Z和J，它们作为同二聚体发挥功能。
