When recA protein pairs circular single strands with linear duplex DNA, the circular strand displaces its homolog from only one end of the duplex molecule and rapidly creates heteroduplex joints that are thousands of base pairs long [DasGupta, C., Shibata, T., Cunningham, R. P. & Radding, C. M. (1980) Cell 22, 437-446]. To examine this apparently polar reaction, we prepared chimeric duplex frag...

The apoE gene exhibits two common polymorphisms that have been associated with both coronary artery disease and Alzheimer's disease. The polymorphisms create the three allelic isoforms E2, E3, and E4 which are encoded by Cys;-Cys, Cys;-Arg, and Arg;-Arg at amino acid positions 112 and 158, respectively. Numerous methods have been described to identify these three apoE alleles although there are...

The DNA repair protein MutS forms clamp-like structures on DNA that search for and recognize base mismatches leading to ATP-transformed signaling clamps. In this study, the mobile MutS clamps were trapped on DNA in a functional state using single-cysteine variants of MutS and thiol-modified homoduplex or heteroduplex DNA. This approach allows stabilization of various transient MutS-DNA complexe...

Single-stranded conformation polymorphism (SSCP) analysis and heteroduplex mobility assays (HMAs) were used to identify and genotype enteric adenoviruses (EAd). The results were compared to those of restriction endonuclease assays, species-specific PCRs, and direct nucleotide sequence analyses. Of the 31 stool samples tested, 15 isolates were identified as EAd and 7 were identified as nonenteri...

It is shown that the mutagen base analogue 2-aminopurine is hydrogen-bonded at its 1-ring position when annealed with cytosine in DNA. The presence of stably hydrogen-bonded regions proximal to the 2-aminopurine-cytosine base mispair is a prerequisite for the occurrence of two hydrogen bonds coupling the bases at their 1-3- and 2-2-positions. We consider the possibility that, in the resulting h...

The "ends-out" or omega (Omega)-form gene replacement vector is used routinely to perform targeted genome modification in a variety of species and has the potential to be an effective vehicle for gene therapy. However, in mammalian cells, the frequency of this reaction is low and the mechanism unknown. Understanding molecular features associated with gene replacement is important and may lead t...

During meiotic recombination in the yeast Saccharomyces cerevisiae, heteroduplexes are formed as an intermediate in the exchange process. In the formation of an asymmetric heteroduplex, one chromosome acts as a donor of a single DNA strand and the other acts as a recipient. We present genetic evidence that the nontranscribed strand is donated more frequently than the transcribed strand in spore...