Structure and function of the PWI motif: a novel nucleic acid-binding domain that facilitates pre-mRNA processing.
The PWI motif is a highly conserved domain of unknown function in the SRm160 splicing and 3'-end cleavage-stimulatory factor, as well as in several other known or putative pre-mRNA processing components. We show here that the PWI motif is a new type of RNA/DNA-binding domain that has an equal preference for single- and double-stranded nucleic acids. Deletion of the motif prevents SRm160 from binding RNA and stimulating 3'-end cleavage, and its substitution with a heterologous RNA-binding domain restores these functions. The NMR solution structure of the SRm160-PWI motif reveals a novel, four-helix bundle and represents the first example of an alpha-helical fold that can bind single-stranded (ss)RNA. Structure-guided mutagenesis indicates that the same surface is involved in RNA and DNA binding and requires the cooperative action of a highly conserved, adjacent basic region. Thus, the PWI motif is a novel type of nucleic acid-binding domain that likely has multiple important functions in pre-mRNA processing, including SRm160-dependent stimulation of 3'-end formation.
Szymczyna
Blair R
BR
Ontario Cancer Institute, University of Toronto, Toronto, Ontario, Canada M5G 2M9.
Bowman
John
J
McCracken
Susan
S
Pineda-Lucena
Antonio
A
Lu
Ying
Y
Cox
Brian
B
Lambermon
Mark
M
Graveley
Brenton R
BR
Arrowsmith
Cheryl H
CH
Blencowe
Benjamin J
BJ
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D034961:Antigens, Nuclear / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D017124:Conserved Sequence; D006367:HeLa Cells; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D034521:Nuclear Matrix-Associated Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D009696:Nucleic Acids / Q000378:metabolism; D011487:Protein Conformation; D012322:RNA Precursors / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D012326:RNA Splicing; D016601:RNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017384:Sequence Deletion
D034961:Antigens, Nuclear; D034521:Nuclear Matrix-Associated Proteins; D009696:Nucleic Acids; D012322:RNA Precursors; D016601:RNA-Binding Proteins; C111710:SRRM1 protein, human