Retinoblastoma susceptibility genes contain significant runs of oligoguanine at their 5' ends. Oligonucleotides having these sequences underwent complex formation in the presence of sodium ions, in which there was association of four strands. Formation of this structure was completely prevented if guanine was replaced by 7-deazaguanine, indicating the… (More)
DNA double-strand breaks (DSBs) can be repaired by homologous recombination (HR), which can involve Holliday junction (HJ) intermediates that are ultimately resolved by nucleolytic enzymes. An N-terminal fragment of human GEN1 has recently been shown to act as a Holliday junction resolvase, but little is known about the role of GEN-1 in vivo. Holliday… (More)
Kink turns (k-turns) are important structural motifs that create a sharp axial bend in RNA. Most conform to a consensus in which a three-nucleotide bulge is followed by consecutive G*A and A*G base pairs, and when these G*A pairs are modified in vitro this generally leads to a failure to adopt the k-turn conformation. Kt-23 in the 30S ribosomal subunit of… (More)
Kink turns (k-turns) are widespread elements in RNA that mediate tertiary contacts by kinking the helical axis. We have found that the ability of k-turns to undergo ion-induced folding is conferred by a single base pair that follows the conserved A·G pairs, that is, the 3b·3n position. A Watson-Crick pair leads to an inability to fold in metal ions alone,… (More)
The k-junction is a structural motif in RNA comprising a three-way helical junction based upon kink turn (k-turn) architecture. A computer program written to examine relative helical orientation identified the three-way junction of the Arabidopsis TPP riboswitch as an elaborated k-turn. The Escherichia coli TPP riboswitch contains a related k-junction, and… (More)
With the growing number of crystal structures of RNA and RNA-protein complexes, a critical next step is understanding the dynamic solution behavior of these entities in terms of conformational ensembles and energy landscapes. To this end, we have used X-ray scattering interferometry (XSI) to probe the ubiquitous RNA kink-turn motif and its complexes with… (More)
Oligoribonucleotides containing a 5'-phosphorothiolate linkage have provided effective tools to study the mechanisms of RNA catalysis, allowing resolution of kinetic ambiguity associated with mechanistic dissection and providing a strategy to establish linkage between catalysis and specific functional groups. However, challenges associated with their… (More)
An HPL program is described which constructs and draws circular restriction maps given a set of cleavage sites, together with deletion of insertion data if required. This program is of great use in the routine interpretation of restriction patterns for the analysis of recombinant DNA molecules.