| First Author | Yang XC | Year | 2009 |
| Journal | Mol Cell Biol | Volume | 29 |
| Issue | 15 | Pages | 4045-56 |
| PubMed ID | 19470752 | Mgi Jnum | J:151443 |
| Mgi Id | MGI:4353869 | Doi | 10.1128/MCB.00296-09 |
| Citation | Yang XC, et al. (2009) Three proteins of the U7-specific Sm ring function as the molecular ruler to determine the site of 3'-end processing in mammalian histone pre-mRNA. Mol Cell Biol 29(15):4045-56 |
| abstractText | Cleavage of histone pre-mRNAs at the 3' end is guided by the U7 snRNP, which is a component of a larger 3'-end processing complex. To identify other components of this complex, we isolated proteins that stably associate with a fragment of histone pre-mRNA containing all necessary processing elements and a biotin affinity tag at the 5' end. Among the isolated proteins, we identified three well-characterized processing factors: the stem-loop binding protein (SLBP), which interacts with the stem-loop structure upstream of the cleavage site, and both Lsm11 and SmB, which are components of the U7-specific Sm ring. We also identified 3'hExo/Eri-1, a multifunctional 3' exonuclease that is known to trim the 3' end of 5.8S rRNA. 3'hExo primarily binds to the downstream portion of the stem-loop structure in mature histone mRNA, with the upstream portion being occupied by SLBP. The two proteins bind their respective RNA sites in a cooperative manner, and 3'hExo can recruit SLBP to a mutant stem-loop that itself does not interact with SLBP. UV-cross-linking studies used to characterize interactions within the processing complex demonstrated that 3'hExo also interacts in a U7-dependent manner with unprocessed histone pre-mRNA. However, this interaction is not required for the cleavage reaction. The region between the cleavage site and the U7-binding site interacts with three low-molecular-weight proteins, which were identified as components of the U7-specific Sm core: SmB, SmD3, and Lsm10. These proteins likely rigidify the substrate and function as the molecular ruler in determining the site of cleavage. |
