OBJECTIVE To localize foci of single-stranded (ss) DNA in sperm nuclei of fertile and infertile men. DESIGN Prospective, observational study. SETTING University infertility clinic. PATIENT(S) Semen samples from 12 consecutive asthenoteratospermic men presenting for infertility evaluation and 5 consecutive fertile men presenting for vasectomy. INTERVENTION(S) Semen analysis, semen proces...

Processing of DNA in replication, repair and recombination pathways in cells of all organisms requires the participation of at least one major single-stranded DNA (ssDNA)-binding protein. This protein protects ssDNA from nucleolytic damage, prevents hairpin formation and blocks DNA reannealing until the processing pathway is successfully completed. Many ssDNA-binding proteins interact physicall...

Bright blue luminescent graphene quantum dots (GQDs) with major graphitic structured nanocrystals and a photoluminescence (PL) quantum yield of 15.5% were synthesized and used to monitor DNA damage. The GQDs were prepared by ultraviolet irradiation without using a chemical agent. The as-prepared GQDs showed excitation-dependent PL and stable electrochemiluminescence (ECL) behaviors. Gold nanopa...

Processing of DNA in replication, repair and recombination pathways in cells of all organisms requires the participation of at least one major single-stranded DNA (ssDNA)-binding protein. This protein protects ssDNA from nucleolytic damage, prevents hairpin formation and blocks DNA reannealing until the processing pathway is successfully completed. Many ssDNA-binding proteins interact physicall...

The RecA protein-single-stranded DNA (ssDNA) filament can bind a second DNA molecule. Binding of ssDNA to this secondary site shows specificity, in that polypyrimidinic DNA binds to the RecA protein-ssDNA filament with higher affinity than polypurinic sequences. The affinity of ssDNA, which is identical in sequence to that bound in the primary site, is not always greater than that of nonhomolog...

Robust single-stranded DNA (ssDNA) microarrays are created by attaching amine-modified oligonucleotides to a monolayer of poly(L-glutamic acid) (pGlu) that is electrostatically adsorbed onto a chemically modified gold thin film. This surface attachment chemistry methodology is first characterized with a combination of polarization-modulation Fourier transform infrared (PM-FTIR) spectroscopy and...

Rad51, Rad52, and RPA play central roles in homologous DNA recombination. Rad51 mediates DNA strand exchange, a key reaction in DNA recombination. Rad52 has two distinct activities: to recruit Rad51 onto single-strand (ss)DNA that is complexed with the ssDNA-binding protein, RPA, and to anneal complementary ssDNA complexed with RPA. Here, we report that Rad52 promotes annealing of the ssDNA str...

The molecular role of the RecF protein in loading RecA protein onto single-stranded DNA (ssDNA)-binding protein-coated ssDNA has been obscured by the facility with which the RecO and RecR proteins alone perform this function. We now show that RecFOR and RecOR define distinct RecA loading functions that operate optimally in different contexts. RecFOR, but not RecOR, is most effective when RecF(R...

The DNA repair protein RAD52 is an emerging therapeutic target of high importance for BRCA-deficient tumors. Depletion of RAD52 is synthetically lethal with defects in tumor suppressors BRCA1, BRCA2 and PALB2. RAD52 also participates in the recovery of the stalled replication forks. Anticipating that ssDNA binding activity underlies the RAD52 cellular functions, we carried out a high throughput...

The properties of the high-affinity single-stranded DNA (ssDNA) binding state of Escherichia coli recA protein have been studied. We find that all of the nucleoside triphosphates that are hydrolyzed by recA protein induce a high-affinity ssDNA binding state. The effect of ATP binding to recA protein was partially separated from the ATP hydrolytic event by substituting calcium chloride for magne...