TrwB is the conjugative coupling protein of plasmid R388. TrwBDeltaN70 contains the soluble domain of TrwB. It was constructed by deletion of trwB sequences containing TrwB N-proximal transmembrane segments. Purified TrwBDeltaN70 protein bound tightly the fluorescent ATP analogue TNP-ATP (K(s) = 8.7 microM) but did not show measurable ATPase or GTPase activity. A single ATP binding site was fou...

A DNase protection technique is described and applied to the interaction of three lac control proteins with supercoiled lac DNA. The technique uses end-labeled oligonucleotide primers to probe specific DNA regions as an alternative to protocols requiring restriction endonuclease cleavage or blotting. Thus DNA may be probed with high resolution in its native state. It is demonstrated that the in...

The binding interaction of novel podophyllotoxin derivative, (3R,4R)-4-((benzo[d][1,3]dioxol-5-yl)methyl)-dihydro-3-(hydroxy(3,4-dimethoxyphenyl) methyl) furan-2(3H)-one (PPT), with calf thymus DNA (ctDNA) has been examined using UV-Visible absorption spectrophotometry, fluorescence spectroscopy, viscosity measurement and molecular docking studies. UV-Vis absorption results showed hyperchromic ...

I-SceI is a homing endonuclease that specifically cleaves an 18-bp double-stranded DNA. I-SceI exhibits a strong preference for cleaving the bottom strand DNA. The published structure of I-SceI bound to an uncleaved DNA substrate provided a mechanism for bottom strand cleavage but not for top strand cleavage. To more fully elucidate the I-SceI catalytic mechanism, we determined the X-ray struct...

Purified vaccinia virus DNA topoisomerase I forms a cleavable complex with duplex DNA at a conserved sequence element 5'(C/T)CCTTdecreases in the incised DNA strand. DNase I footprint studies show that vaccinia topoisomerase protects the region around the site of covalent adduct formation from nuclease digestion. On the cleaved DNA strand, the protected region extends from +13 to -13 (+1 being ...

continuous labelling of callus with h-thymidine results in intermittent peaks of h-dna per chloroplast, showing synchrony of division. the increase in h-dna could be due to several replication rounds, and the drop to successive plastid divisions without intervening dna synthesis. the level of dna-binding proteins in the chloroplast parallels the peaks of plastidal dna synthesis; such proteins c...

The photoactivatable modified oligonucleotides were used to investigate direct contacts formed by the type IIE EcoRII restriction endonuclease and T/A bases of its recognition site (5'-CCT/AGG). dimer consists a central catalytic core, made two C-terminal endonuclease-like domains (EcoRII-C) from different subunits, N-terminal effector DNA binding (EcoRII-N). According co-crystal structure isol...

Viral DNA binding proteins that direct nucleases or other protein domains to viral DNA in lytically or latently infected cells may provide a novel approach to modulate viral gene expression or replication. Cervical carcinogenesis is initiated by high-risk human papillomavirus (HPV) infection, and viral DNA persists in the cancer cells. To test whether a DNA binding domain of a papillomavirus pr...