Tang J, Abovich N, Rosbash M
Howard Hughes Medical Institute, Brandeis University, Waltham, Massachusetts 02254, USA.
Mol Cell Biol. 1996 Jun;16(6):2787-95. doi: 10.1128/MCB.16.6.2787.
The inessential yeast gene MUD2 encodes a protein factor that contributes to U1 small nuclear ribonucleoprotein particle (snRNP)-pre-mRNA complex (commitment complex) formation. To identify other genes that contribute to this early splicing step, we performed a synthetic lethal screen with a MUD2 deletion strain. The first characterized gene from this screen, MSL1 (MUD synthetic lethal 1), encodes the yeast homolog of the well studied mammalian snRNP protein U2B". The yeast protein (YU2B") is a component of yeast U2 snRNP, and it is related to other members of the UIA-U2B" family, the human U2B" protein, the human U1A protein, and the yeast U1A protein. It binds in vitro to its RNA target, U2 snRNA stem-loop IV, without a protein cofactor, and the target resembles more closely the U1 snRNA binding site of the human U1A protein than it does the U2 snRNA binding site of human U2B". Surprisingly, the YU2B" protein lacks a C-terminal RNA binding domain, which is conserved in all other family members. Possible functional and evolutionary relationships among these proteins are discussed.
非必需酵母基因MUD2编码一种蛋白质因子，该因子有助于U1小核核糖核蛋白颗粒（snRNP）-前体mRNA复合物（起始复合物）的形成。为了鉴定有助于这一早期剪接步骤的其他基因，我们用MUD2缺失菌株进行了合成致死筛选。从该筛选中鉴定出的第一个基因MSL1（MUD合成致死1），编码与经过充分研究的哺乳动物snRNP蛋白U2B″同源的酵母蛋白。酵母蛋白（YU2B″）是酵母U2 snRNP的一个组分，并且它与U1A-U2B″家族的其他成员、人U2B″蛋白、人U1A蛋白以及酵母U1A蛋白相关。它在体外无需蛋白质辅因子即可结合其RNA靶标U2 snRNA茎环IV，并且该靶标与人U1A蛋白的U1 snRNA结合位点相比，与人U2B″蛋白的U2 snRNA结合位点更为相似。令人惊讶的是，YU2B″蛋白缺乏在所有其他家族成员中都保守的C端RNA结合结构域。文中讨论了这些蛋白质之间可能的功能和进化关系。
