Anti-Rex aptamers as mimics of the Rex-binding element.
RNA molecules that bind tightly and specifically to a Rex fusion protein have been isolated from a conformationally constrained pool of random sequence RNAs. The anti-Rex aptamers effectively mimic several features of the wild-type Rex-binding element (XBE). The highest-affinity aptamers effectively compete with the wild-type XBE for binding to the RNA-binding domain of Rex, an arginine-rich motif (ARM), but do not bind to the functionally analogous Rev protein or its ARM. However, characteristic sequence and structural motifs found in some of the anti-Rex aptamers may provide insights into how the Rex protein can interact with other viral RNAs, such as the Rev-responsive element. The anti-Rex aptamers can functionally substitute for the XBE in vivo, a result which supports a previously proposed model for mRNA transport in which the viral genome serves as a platform for assembling a nucleoprotein complex that can co-opt the cellular transport apparatus. Overall, these studies suggest that anti-Rex aptamers may serve as RNA decoys of the Rex protein.
Baskerville
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Department of Biology, Indiana University at Bloomington, Bloomington, Indiana, USA.
Zapp
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Ellington
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AD
D001692:Biological Transport; D015694:Gene Products, rev / Q000502:physiology; D016370:Gene Products, rex / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D011119:Polynucleotides; D012333:RNA, Messenger / Q000378:metabolism; D012367:RNA, Viral / Q000378:metabolism*; D020218:Response Elements; D014779:Virus Replication
D015694:Gene Products, rev; D016370:Gene Products, rex; D011119:Polynucleotides; D012333:RNA, Messenger; D012367:RNA, Viral