A variety of methods have been developed to screen for genetic mutations. Most rely on the comparative analysis of polymerase chain reaction (PCR) products. Single-strand conformational polymorphism (4), the most widely used technique, relies on sequence-dependent conformational electrophoretic mobility differences between wild-type (WT) and mutant strands; whereas, heteroduplex analysis (5,8),...

We have shown previously that heteroduplexes containing single-stranded loops are repaired efficiently in monkey cells, but not always correctly: 2% of the repair products acquired mutations within a 350 base-pair target (Weiss, U. and Wilson, J.H., Proc. Natl. Acad. Sci. USA 87:1123-1126, 1987). The structures of the mutant genomes, which are described here, are consistent with an error-prone ...

G234 is a large silent deletion located in the middle of gene b2, which controls spore pigmentation in Ascobolus immersus. Its gene conversion directionality was studied in asci, which show evidence of heteroduplex DNA at flanking markers, and was compared to the behavior of closely linked single-base-pair insertions or deletions. We found that with the G234 deletion, the genotype of the donor ...

We investigated the interaction of the short peptide nucleic acid (PNA) strand [acccca]-PNA with oligodeoxynucleotides containing one, two, or four tracts of TGGGGT units. Electrospray ionization mass spectrometry allowed exploring the wide variety of complex stoichiometries that were found to coexist in solution. In water, the PNA strand forms short heteroduplexes with the complementary DNA se...

The recA protein of Escherichia coli promotes the complete exchange of strands between full-length linear duplex and single-stranded circular phi X174 DNA molecules. Analysis of the reaction by electron microscopy confirms that D loops containing short heteroduplex regions are rapidly formed at the ends of the linear duplex, followed by a relatively slow branch migration that converts the D loo...

RadA (also known as 'Sms') is a highly conserved protein, found in almost all eubacteria and plants, with sequence similarity to the RecA strand exchange protein and a role in homologous recombination. We investigate here the biochemical properties of the E. coli RadA protein and several mutant forms. RadA is a DNA-dependent ATPase, a DNA-binding protein and can stimulate the branch migration p...

Eosinophilic pustular folliculitis is characterized by an eosinophil-rich inflammatory follicular and perifollicular infiltrate primarily centred at the level of the follicular isthmus and sebaceous duct. Follicular mucinosis has been observed in lesions of eosinophilic pustular folliculitis. Clinical and histological features of eosinophilic pustular folliculitis with follicular mucinosis and ...

Rad51 is a key protein in homologous recombination performing homology search and DNA strand invasion. After DNA strand exchange Rad51 protein is stuck on the double-stranded heteroduplex DNA product of DNA strand invasion. This is a problem, because DNA polymerase requires access to the invading 3'-OH end to initiate DNA synthesis. Here we show that, the Saccharomyces cerevisiae dsDNA motor pr...

The RecE recombination pathway is active in Escherichia coli recB recC sbcA mutants. To isolate and characterize products and intermediates of RecE-mediated, break-induced, intramolecular recombination, we infected recB recC sbcA mutants, expressing EcoRI endonuclease, with chimeric lambda phages that allow EcoRI-mediated release of cloned linear recombination substrates. Substrates with direct...

The RecBCD enzyme of Escherichia coli functions in the seemingly disparate roles of homologous recombination and the degradation of DNA. Which of these two roles it assumes is regulated by the 8-base recombination hotspot, Chi. Using double-stranded DNA substrates that are heteroduplex at the Chi locus we have established the determinants for Chi recognition. Our results show that an actively t...