Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:5.99.1.2 (topoisomerase)
 9,166 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

How plant organs grow to reach their final size is an important but largely unanswered question. Here, we describe an Arabidopsis thaliana mutant, brassinosteroid-insensitive4 (bin4), in which the growth of various organs is dramatically reduced. Small organ size in bin4 is primarily caused by reduced cell expansion associated with defects in increasing ploidy by endoreduplication. Raising nuclear DNA content in bin4 by colchicine-induced polyploidization partially rescues the cell and organ size phenotype, indicating that BIN4 is directly and specifically required for endoreduplication rather than for subsequent cell expansion. BIN4 encodes a plant-specific, DNA binding protein that acts as a component of the plant DNA topoisomerase VI complex. Loss of BIN4 triggers an ATM- and ATR-dependent DNA damage response in postmitotic cells, and this response coincides with the upregulation of the cyclin B1;1 gene in the same cell types, suggesting a functional link between DNA damage response and endocycle control.
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PMID:BIN4, a novel component of the plant DNA topoisomerase VI complex, is required for endoreduplication in Arabidopsis. 1805 5

An antitumour chemotherapeutic, daunorubicin (DNR), produced by Streptomyces peucetius exhibits cytotoxic activity through topoisomerase-mediated interaction with DNA, thereby inhibiting DNA replication and repair and RNA and protein synthesis. It is synthesized by the type II polyketide pathway. Understanding molecular mechanisms that drive expression of antibiotic biosynthetic genes in response to diverse signals and chemical inducers is of considerable interest. Intergenic DNA between regulatory genes dnrN and dnrO of DNR biosynthesis pathway in S. peucetius has a promoter for transcription of dnrN in one strand and three promoters in the opposite strand for dnrO. Studies have shown that DnrO binds to a specific sequence in this region to activate transcription of dnrN. In the present study, using biotinylated intergenic DNA in combination with streptavidin magnetic beads, we have purified a protein that binds to this target sequence. The protein has been characterized by nano LC ESI MS/MS mass spectrometry. Sequence similarity searches for effective identification of protein by genome databases comparisons led to identification of a sequence-specific DNA binding protein that exhibits dihydrolipoamide dehydrogenase (DLDH) activity suggesting that this protein may be involved in regulation of DNR biosynthesis.
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PMID:A novel protein that binds to dnrN-dnrO intergenic region of Streptomyces peucetius purified by DNA affinity capture has dihydrolipoamide dehydrogenase activity. 1948 Nov 52

DNA structure and topology pervasively influence aspects of DNA metabolism including replication, transcription and segregation. However, the effects of DNA topology on DNA-protein interactions have not been systematically explored due to limitations of standard affinity assays. We developed a method to measure protein binding affinity dependence on the topology (topological linking number) of supercoiled DNA. A defined range of DNA topoisomers at equilibrium with a DNA binding protein is separated into free and protein-bound DNA populations using standard nitrocellulose filter binding techniques. Electrophoretic separation and quantification of bound and free topoisomers combined with a simple normalization procedure provide the relative affinity of the protein for the DNA as a function of linking number. Employing this assay we measured topology-dependent DNA binding of a helicase, a type IB topoisomerase, a type IIA topoisomerase, a non-specific mitochondrial DNA binding protein and a type II restriction endonuclease. Most of the proteins preferentially bind negatively supercoiled DNA but the details of the topology-dependent affinity differ among proteins in ways that expose differences in their interactions with DNA. The topology-dependent binding assay provides a robust and easily implemented method to probe topological influences on DNA-protein interactions for a wide range of DNA binding proteins.
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PMID:A robust assay to measure DNA topology-dependent protein binding affinity. 2555 13

Single-stranded DNA binding protein (Ssb) of Deinococcus radiodurans comprises N- and C-terminal oligonucleotide/oligosaccharide binding (OB) folds connected by a beta hairpin connector. To assign functional roles to the individual OB folds, we generated three Ssb variants: SsbN (N-terminal without connector), SsbNC (N-terminal with connector) and SsbC (C-terminal), each harboring one OB fold. Both SsbN and SsbNC displayed weak single-stranded DNA (ssDNA) binding activity, compared to the full-length Ssb (SsbFL). The level of ssDNA binding activity displayed by SsbC was intermediate between SsbFL and SsbN. SsbC and SsbFL predominantly existed as homo-dimers while SsbNC/SsbN formed different oligomeric forms. In vitro, SsbNC or SsbN formed a binary complex with SsbC that displayed enhanced ssDNA binding activity. Unlike SsbFL, Ssb variants were able to differentially modulate topoisomerase-I activity, but failed to stimulate Deinococcal RecA-promoted DNA strand exchange. The results suggest that the C-terminal OB fold is primarily responsible for ssDNA binding. The N-terminal OB fold binds weakly to ssDNA but is involved in multimerization.
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PMID:Functional roles of N-terminal and C-terminal domains in the overall activity of a novel single-stranded DNA binding protein of Deinococcus radiodurans. 2597 64


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