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T L Symensma

Publications and source records attributed to T L Symensma.

4 recordsLinked to original sources
PubMed1999

Polyvalent Rev decoys act as artificial Rev-responsive elements.

Interactions between Rev and the Rev-responsive element (RRE) control the order, rate, and extent of gene expression in human immunodeficiency virus type 1. Rev decoys may therefore prove to be useful RNA therapeutics for the treatment of AIDS. To improve upon the current generation of Rev decoys that bind single Rev molecules, it would be useful to generate polyvalent Rev decoys that could bind multiple Rev molecules. J. Kjems and P. A. Sharp (J. Virol. 67:4769-4776, 1993) originally constructed functional polyvalent Rev decoys, but the structural context of these polyvalent decoys remains unclear, and it has been argued that the individual decoys were either structurally discrete (Kjems and Sharp, J. Virol. 67:4769-4776, 1993) or were part of an extended helix (R. W. Zemmel et al., Mol. Biol. 258:763-777, 1996). To resolve the differences between these models, we have designed and synthesized concatemers of Rev-binding elements (RBEs) that fold to form multiple, discrete, high-affinity Rev-binding sites. We find that the concatenated RBEs can facilitate the cytoplasmic transport of viral mRNAs and therefore likely bind multiple Rev molecules. These artificial RREs may simultaneously sequester Rev and hinder access to the cellular transport machinery.

Animals↗
PubMed1996

RNA aptamers selected to bind human immunodeficiency virus type 1 Rev in vitro are Rev responsive in vivo.

RNA aptamers (binding sequences) that can interact tightly and specifically with the human immunodeficiency virus type 1 Rev protein have previously been selected from random sequence pools. Although the selected sequences compete with the wild-type Rev-binding element (RBE) in vitro, it was not known whether they would be able to functionally replace the RBE in vivo. Two aptamers that were different from the wild-type RBE in terms of both primary sequence and secondary structure were inserted into the full-length Rev-responsive element (RRE) in place of the RBE. The hybrid RREs were assayed for their ability to mediate Rev function in vivo using a reporter system. The aptamers were found to be functionally equivalent to the wild-type element when the assay system was saturated with Rev and better than the wild-type element when Rev was limiting. These results demonstrate that the affinity of the primary Rev-binding element rather than its particular sequence may be most responsible for conferring Rev responsiveness on viral mRNAs. Moreover, the fact that increased binding ability can lead to increased Rev responsiveness suggests that cellular factors do not directly influence the Rev:RBE interaction. Finally, since sequences distinct from the RBE are found to be Rev responsive, it may be possible for the RBE to readily mutate in response to drugs or gene therapy reagents that target the Rev:RBE interaction.

Animals↗
PubMed1995

A simple code for protein:RNA interactions.

The Tat and Rev proteins of HIV-1 and the Rex protein of HTLV-I do not interact with their cognate ligands via a particular structural motif but instead specifically recognize RNA molecules by using agglomerations of arginine residues (1). These proteins are members of the so-called arginine-rich motif (ARM) family. There is little data to support (or contradict) the hypothesis that a few simple arginine:RNA interactions govern how ARMs recognize their viral targets. Not only is it unclear how ARM proteins other than Tat interact with their cognate RNA ligands, for the most part it is not even known how structurally complex these RNA ligands are. In order to fully explore the range of RNA sequences and structures that can bind to ARMs we have carried out in vitro genetic selections with two disparate viral proteins: Rev and Rex.

Arginine↗