The time course of the appearance of intracellular viral DNA has been studied in mouse L cells infected with the single-stranded DNA virus MVM (minute virus of mice) by using a selective extraction procedure. Approximately half of this DNA elutes from hydroxyapatite as single-stranded DNA. It is sensitive to Escherichia coli exonuclease I and shows a sedimentation profile similar to DNA from th...

Double-stranded (ds) RNA induces potent gene silencing, termed RNA interference (RNAi). At an early step in RNAi, an RNaseIII-related enzyme, Dicer (DCR-1), processes long-trigger dsRNA into small interfering RNAs (siRNAs). DCR-1 is also required for processing endogenous regulatory RNAs called miRNAs, but how DCR-1 recognizes its endogenous and foreign substrates is not yet understood. Here we...

Agrobacterium tumefaciens-mediated genetic transformation involves transfer of a single-stranded T-DNA molecule (T strand) into the host cell, followed by its integration into the plant genome. The molecular mechanism of T-DNA integration, the culmination point of the entire transformation process, remains largely obscure. Here, we studied the roles of double-stranded breaks (DSBs) and double-s...

Rad54 and Rad51 are important proteins for the repair of double-stranded DNA breaks by homologous recombination in eukaryotes. As previously shown, Rad51 protein forms nucleoprotein filaments on single-stranded DNA, and Rad54 protein directly interacts with such filaments to enhance synapsis, the homologous pairing with a double-stranded DNA partner. Here we demonstrate that Saccharomyces cerev...

Binding of the 58 kDa monomer and 44 kDa alpha beta dimer forms of terminal deoxynucleotidyl transferase to double stranded DNA was demonstrated by gel retardation and tryptophan fluorescence quenching. The dissociation constants and cooperativity parameters were similar to those that have been determined for binding of these two forms of terminal transferase to single stranded DNA. However, th...

Characterization of proteins binding to the promoters of eukaryotic genes has proved essential for understanding the transcriptional regulation of viral and cellular genes. Because of the low abundance of these proteins in the cell, conventional purification of these molecules has been laborious. In contrast, sequencespecific DNA affinity chromatography has greatly faciliated rapid isolation an...

An Acholeplasma laidlawii variant has been isolated that has a REP- phenotype. The properties of this variant, relative to parental cells, are: (i) it exhibits no change in cell growth kinetics; (ii) it does not propagate single-stranded deoxyribonucleic acid (DNA) mycoplasmaviruses but does propagate double-stranded DNA mycoplasmaviruses; (iii) it converts parental circular single-stranded myc...

The active DNA-dependent ATPase A domain (ADAAD), a member of the SWI2/SNF2 family, has been shown to bind DNA in a structure-specific manner, recognizing DNA molecules possessing double-stranded to single-stranded transition regions leading to ATP hydrolysis. Extending these studies we have delineated the structural requirements of the DNA effector for ADAAD and have shown that the single-stra...

Infection of JLS V-9 (mouse bone marrow) cells with Moloney murine leukemia virus leads to appearance of virus-specific DNA in the low molecular weight DNA fraction from infected cells. Most of this DNA is double-stranded. Two discrete forms of double-stranded DNA, both of molecular weight 6 times 10-6, have been characterized. One of these forms is closed-circular, supercoiled DNA; the other f...