The 68 kDa subunit of mammalian cleavage factor I interacts with the U7 small nuclear ribonucleoprotein and participates in 3'-end processing of animal histone mRNAs.
Metazoan replication-dependent histone pre-mRNAs undergo a unique 3'-cleavage reaction which does not result in mRNA polyadenylation. Although the cleavage site is defined by histone-specific factors (hairpin binding protein, a 100-kDa zinc-finger protein and the U7 snRNP), a large complex consisting of cleavage/polyadenylation specificity factor, two subunits of cleavage stimulation factor and symplekin acts as the effector of RNA cleavage. Here, we report that yet another protein involved in cleavage/polyadenylation, mammalian cleavage factor I 68-kDa subunit (CF I(m)68), participates in histone RNA 3'-end processing. CF I(m)68 was found in a highly purified U7 snRNP preparation. Its interaction with the U7 snRNP depends on the N-terminus of the U7 snRNP protein Lsm11, known to be important for histone RNA processing. In vivo, both depletion and overexpression of CF I(m)68 cause significant decreases in processing efficiency. In vitro 3'-end processing is slightly stimulated by the addition of low amounts of CF I(m)68, but inhibited by high amounts or by anti-CF I(m)68 antibody. Finally, immunoprecipitation of CF I(m)68 results in a strong enrichment of histone pre-mRNAs. In contrast, the small CF I(m) subunit, CF I(m)25, does not appear to be involved in histone RNA processing.
Ruepp
Marc-David
MD
Institute of Cell Biology, University of Bern, CH-3012 Bern, Switzerland.
Vivarelli
Silvia
S
Pillai
Ramesh S
RS
Kleinschmidt
Nicole
N
Azzouz
Teldja N
TN
Barabino
Silvia M L
SM
Schümperli
Daniel
D
D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D006657:Histones / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D051379:Mice; D009154:Mutation; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D026721:RNA 3' End Processing; D012322:RNA Precursors / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins; D020885:Ribonucleoprotein, U7 Small Nuclear / Q000378:metabolism*; D017411:Ribonucleoproteins, Small Nuclear / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D039221:mRNA Cleavage and Polyadenylation Factors / Q000737:chemistry / Q000378:metabolism*
D006657:Histones; C477938:Lsm11 protein, mouse; D021122:Protein Subunits; D012322:RNA Precursors; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D020885:Ribonucleoprotein, U7 Small Nuclear; D017411:Ribonucleoproteins, Small Nuclear; D039221:mRNA Cleavage and Polyadenylation Factors