Structure and RNA interactions of the N-terminal RRM domains of PTB.
The polypyrimidine tract binding protein (PTB) is an important regulator of alternative splicing that also affects mRNA localization, stabilization, polyadenylation, and translation. NMR structural analysis of the N-terminal half of PTB (residues 55-301) shows a canonical structure for RRM1 but reveals novel extensions to the beta strands and C terminus of RRM2 that significantly modify the beta sheet RNA binding surface. Although PTB contains four RNA recognition motifs (RRMs), it is widely held that only RRMs 3 and 4 are involved in RNA binding and that RRM2 mediates homodimerization. However, we show here not only that the RRMs 1 and 2 contribute substantially to RNA binding but also that full-length PTB is monomeric, with an elongated structure determined by X-ray solution scattering that is consistent with a linear arrangement of the constituent RRMs. These new insights into the structure and RNA binding properties of PTB suggest revised models of its mechanism of action.
Simpson
Peter J
PJ
Department of Biological Sciences, Imperial College, South Kensington Campus, Exhibition Road, London SW7 2AZ, UK.
Monie
Tom P
TP
Szendröi
Andrea
A
Davydova
Natalia
N
Tyzack
Jonathan K
JK
Conte
Maria R
MR
Read
Christopher M
CM
Cary
Peter D
PD
Svergun
Dmitri I
DI
Konarev
Peter V
PV
Curry
Stephen
S
Matthews
Stephen
S
D000595:Amino Acid Sequence; D019281:Dimerization; D006801:Humans; D008958:Models, Molecular; D008970:Molecular Weight; D019906:Nuclear Magnetic Resonance, Biomolecular; D038941:Polypyrimidine Tract-Binding Protein / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012313:RNA / Q000378:metabolism*; D016415:Sequence Alignment
D038941:Polypyrimidine Tract-Binding Protein; D012313:RNA