TY - JOUR
T1 - Crystal structure of human UP1, the domain of hnRNP A1 that contains two RNA-recognition motifs
AU - Xu, Rui Ming
AU - Jokhan, Lana
AU - Cheng, Xiaodong
AU - Mayeda, Akila
AU - Krainer, Adrian R.
N1 - Funding Information:
We would like to thank RM Sweet for access to the Biology Department single-crystal diffraction facility at beamline X12-C of the National Synchrotron Light Source, Brookhaven National Laboratory. This facility is supported by the United States Department of Energy, Office of Health and Environmental Research, and by the National Science Foundation. We are grateful to Ai-Ping Dong for assistance with data collection, and to Malcolm Capel for help in cryo-data collection. We thank Steve Munroe, Ewan Birney, Leemor Joshua-Tor, and Margaret O’gara for comments on the manuscript. This work was supported in part by the WM Keck Foundation, the Robertson research fund (RMX), NIH grants GM49245 and GM/OD 52117 (XC), and NCI grant CA13107 (AM and ARK).
PY - 1997
Y1 - 1997
N2 - Background: Heterogeneous nuclear ribonucleoprotein (hnRNP) A1 is one of the most abundant core proteins of hnRNP complexes in metazoan nuclei. It behaves as a global regulator of alternative pre-mRNA splicing by antagonizing the activities of several serine/arginine-rich splicing factors (SR proteins), resulting in the activation of distal alternative 5' splice sites and skipping of optional exons. Purified hnRNP A1 has nucleic acid annealing activity. The protein also shuttles continuously between the nucleus and the cytoplasm, a process mediated by signals within its C-terminal glycine-rich domain. The N-terminal region of human hnRNP A1, termed unwinding protein 1 (UP1), contains two RNA-recognition motifs (RRMs), RRM1 and RRM2. Understanding the structural elements by which hnRNP A1 interacts with RNA will have broad implications for studies of RNA processing. Results: The crystal structure of UP1 has been determined to 1.9 Å resolution. Each RRM independently adopts the characteristic RRM fold, consisting of a four-stranded antiparallel β-pleated sheet and two α helices packed on one side of the β sheet. The two RRMs are antiparallel and held in close contact, mainly by two Arg-Asp ion pairs. As a result, the two four-stranded β sheets are brought together to form an extended RNA-binding surface. A segment of the linker connecting the two RRMs is flexible in the absence of bound RNA, but the general location of the linker suggests that it can make direct contacts with RNA. Comparison with other RRM structures indicates that a short 310 helix, found immediately N-terminal to the first β strand in RRM 1, may interact with RNA directly. Conclusions: The RRM is one of the most common and best characterized RNA-binding motifs. In certain cases, one RRM is sufficient for sequence-specific and high affinity RNA binding; but in other cases, synergy between several RRMs within a single protein is required. This study shows how two RRMs are organized in a single polypeptide. The two independently folded RRMs in UP1 are held together in a fixed geometry, enabling the two RRMs to function as a single entity in binding RNA, and so explaining the synergy between the RRMs. The UP1 structure also suggests that residues which lie outside of the RRMs can make potentially important interactions with RNA.
AB - Background: Heterogeneous nuclear ribonucleoprotein (hnRNP) A1 is one of the most abundant core proteins of hnRNP complexes in metazoan nuclei. It behaves as a global regulator of alternative pre-mRNA splicing by antagonizing the activities of several serine/arginine-rich splicing factors (SR proteins), resulting in the activation of distal alternative 5' splice sites and skipping of optional exons. Purified hnRNP A1 has nucleic acid annealing activity. The protein also shuttles continuously between the nucleus and the cytoplasm, a process mediated by signals within its C-terminal glycine-rich domain. The N-terminal region of human hnRNP A1, termed unwinding protein 1 (UP1), contains two RNA-recognition motifs (RRMs), RRM1 and RRM2. Understanding the structural elements by which hnRNP A1 interacts with RNA will have broad implications for studies of RNA processing. Results: The crystal structure of UP1 has been determined to 1.9 Å resolution. Each RRM independently adopts the characteristic RRM fold, consisting of a four-stranded antiparallel β-pleated sheet and two α helices packed on one side of the β sheet. The two RRMs are antiparallel and held in close contact, mainly by two Arg-Asp ion pairs. As a result, the two four-stranded β sheets are brought together to form an extended RNA-binding surface. A segment of the linker connecting the two RRMs is flexible in the absence of bound RNA, but the general location of the linker suggests that it can make direct contacts with RNA. Comparison with other RRM structures indicates that a short 310 helix, found immediately N-terminal to the first β strand in RRM 1, may interact with RNA directly. Conclusions: The RRM is one of the most common and best characterized RNA-binding motifs. In certain cases, one RRM is sufficient for sequence-specific and high affinity RNA binding; but in other cases, synergy between several RRMs within a single protein is required. This study shows how two RRMs are organized in a single polypeptide. The two independently folded RRMs in UP1 are held together in a fixed geometry, enabling the two RRMs to function as a single entity in binding RNA, and so explaining the synergy between the RRMs. The UP1 structure also suggests that residues which lie outside of the RRMs can make potentially important interactions with RNA.
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U2 - 10.1016/S0969-2126(97)00211-6
DO - 10.1016/S0969-2126(97)00211-6
M3 - Article
C2 - 9115444
AN - SCOPUS:0031569797
SN - 0969-2126
VL - 5
SP - 559
EP - 570
JO - Structure
JF - Structure
IS - 4
ER -