Symplekin and multiple other polyadenylation factors participate in 3'-end maturation of histone mRNAs.
Most metazoan messenger RNAs encoding histones are cleaved, but not polyadenylated at their 3' ends. Processing in mammalian cell extracts requires the U7 small nuclear ribonucleoprotein (U7 snRNP) and an unidentified heat-labile factor (HLF). We describe the identification of a heat-sensitive protein complex whose integrity is required for histone pre-mRNA cleavage. It includes all five subunits of the cleavage and polyadenylation specificity factor (CPSF), two subunits of the cleavage stimulation factor (CstF), and symplekin. Reconstitution experiments reveal that symplekin, previously shown to be necessary for cytoplasmic poly(A) tail elongation and translational activation of mRNAs during Xenopus oocyte maturation, is the essential heat-labile component. Thus, a common molecular machinery contributes to the nuclear maturation of mRNAs both lacking and possessing poly(A), as well as to cytoplasmic poly(A) tail elongation.
Kolev
Nikolay G
NG
Howard Hughes Medical Institute, Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06536, USA.
Steitz
Joan A
JA
D000818:Animals; D002474:Cell-Free System; D039223:Cleavage And Polyadenylation Specificity Factor / Q000378:metabolism; D039241:Cleavage Stimulation Factor / Q000378:metabolism; D004330:Drosophila; D006367:HeLa Cells; D006657:Histones / Q000096:biosynthesis*; D006801:Humans; D008297:Male; D046912:Multiprotein Complexes / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D009865:Oocytes / Q000378:metabolism; D026721:RNA 3' End Processing / Q000502:physiology*; D012322:RNA Precursors / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D020885:Ribonucleoprotein, U7 Small Nuclear / Q000378:metabolism; D014981:Xenopus
D039223:Cleavage And Polyadenylation Specificity Factor; D039241:Cleavage Stimulation Factor; D006657:Histones; D046912:Multiprotein Complexes; D009687:Nuclear Proteins; D012322:RNA Precursors; D012333:RNA, Messenger; D020885:Ribonucleoprotein, U7 Small Nuclear; C101043:SYMPK protein, human