Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:Q02556 (DNA-binding domain)
 6,431 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Several distinct mutations in the ligand-binding domain of the beta form of the thyroid hormone receptor have been reported in kindreds with the autosomal dominant syndrome of generalized resistance to thyroid hormone (GRTH). GRTH receptor mutants are functionally inactive but capable of inhibiting normal receptor function in transient expression studies. We examined the possibility that this dominant negative activity of the GRTH mutants involves competition for receptor binding to DNA. Mutations introduced into either the T3 ligand-binding domain (LBD) or into the DNA-binding domain (DBD) of the receptor eliminated the transcriptional activity of the receptor. In cotransfection experiments, the LBD mutants, but not the DBD mutants, inhibited the transcriptional activity of the normal receptor. The inhibitory activity of the LBD mutants was abolished by the introduction of an additional mutation into the DBD, suggesting that the DBD is required for dominant negative activity. A chimeric receptor, in which the DNA-binding domain of the thyroid hormone receptor was exchanged with the homologous region in the glucocorticoid receptor (GTG), was used to study thyroid hormone receptor competition for GTG interactions with thyroid receptor target sequences. In the absence of thyroid hormone, the normal thyroid hormone receptor inhibited dexamethasone stimulated transcription by GTG. The transcriptional activity of GTG was also inhibited by the LBD mutants but not by a DBD mutant of the thyroid hormone receptor. These results indicate that the thyroid hormone receptor mutations that occur in GRTH compete with normal receptors at DNA-binding sites in target genes to block normal receptor function.
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PMID:Thyroid hormone receptor mutants that cause resistance to thyroid hormone. Evidence for receptor competition for DNA sequences in target genes. 161 99

The Rickettsia prowazekii (Rp) gyrA gene, which codes for a subunit of DNA gyrase in this obligate intracellular bacterium, has been isolated and characterized. Nucleotide sequence analysis revealed an open reading frame (ORF), initiating with a GTG start codon, of 2718 bp that could encode a protein of 905 amino acids (aa) with a calculated M(r) of 101,048. The Rp gyrase subunit A (GyrA), when compared to GyrA analogs of other bacterial species, exhibited 43 to 50% identity. Alignment of the Rp GyrA aa sequence with the other analogs revealed the presence of a span of additional aa within the putative DNA-binding domain. The lack of an ORF within 865 bp upstream from the Rp gyrA demonstrates a Rp gene organization different from that of characterized gyrA from other species. Despite the similarity to Escherichia coli GyrA, Rp GyrA did not complement an E. coli gyrA temperature-sensitive mutant. However, Rp gyrA was dominant to an E. coli gyrA96 nalidixic-acid-resistant (NalR) mutant, conferring Nal sensitivity when introduced into the NalR E. coli strain.
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PMID:Sequence analysis of the Rickettsia prowazekii gyrA gene. 782 73

The prokaryotic enhancer-binding protein NIFA is a multidomain transcriptional activator that catalyzes the formation of open complexes at nitrogen fixation (nif) promoters by a specialized form of RNA polymerase containing sigma 54. The NIFA protein from Klebsiella pneumoniae consists of three domains: the N-terminal domain of unknown function; the central catalytic domain, which is sufficient for transcriptional activation; and the C-terminal DNA-binding domain. Purified fusion proteins between maltose-binding protein (MBP) and NIFA deleted of its N-terminal domain (MBP-delta N-NIFA) or its C-terminal domain (MBP-NIFA-delta C) activated transcription from the K. pneumoniae nifH promoter both in vitro and in vivo. We previously showed that the same was true for a fusion between MBP and the central domain of NIFA. These results indicate that NIFA is sufficiently modular for all fusions carrying its catalytic domain to be active. Unexpectedly, however, simple predictions regarding the location of determinants of the heat lability and insolubility of NIFA, which were based on previous studies of its isolated central and C-terminal domains, were not borne out. Contrary to a previous report from this laboratory, we found that the in vitro start site of transcription for the K. pneumoniae nifH operon could be either of two adjacent G residues, as others had reported in vivo. This was true independent of the activator, i.e., with MBP-NIFA and MBP-delta N-NIFA and with the homologous activator NTRC. When open complexes were formed with GTP as the activating nucleotide, the upstream G residue was probably as a consequence of initiation of transcription.
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PMID:In vitro studies of the domains of the nitrogen fixation regulatory protein NIFA. 800 17

The GTP-dependent restriction enzyme McrBC consists of two polypeptides: one (McrB) that is responsible for GTP binding and hydrolysis as well as DNA binding and another (McrC) that is responsible for DNA cleavage. It recognizes two methylated or hemimethylated RC sites (R(m)C) at a distance of approximately 30 to more than 2000 base pairs and cleaves the DNA close to one of the two R(m)C sites. This process is strictly coupled to GTP hydrolysis and involves the formation of high-molecular mass complexes. We show here using footprinting techniques, surface plasmon resonance, and scanning force microscopy experiments that in the absence of McrC, McrB binds to a single R(m)C site. If a second R(m)C site is present on the DNA, it is occupied independently by McrB. Whereas the DNA-binding domain of McrB forms 1:1 complexes with each R(m)C site and shows a clear footprint on both R(m)C sites, full-length McrB forms complexes with a stoichiometry of at least 4:1 at each R(m)C site, resulting in a slightly more extended footprint. In the presence of McrC, McrB forms high-molecular mass complexes of unknown stoichiometry, which are considerably larger than the complexes formed with McrB alone. In these complexes and when GTP is present, the DNA is cleaved next to one of the R(m)C sites at distances differing by one to five helical turns, suggesting that in the McrBC-DNA complex only a few topologically well-defined phosphodiester bonds of the DNA are accessible for the nucleolytic center of McrC.
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PMID:The GTP-dependent restriction enzyme McrBC from Escherichia coli forms high-molecular mass complexes with DNA and produces a cleavage pattern with a characteristic 10-base pair repeat. 1195 74

Class III adenylyl cyclases usually possess six highly conserved catalytic residues. Deviations in these canonical amino acids are observed in several putative adenylyl cyclase genes as apparent in several bacterial genomes. This suggests that a variety of catalytic mechanisms may actually exist. The gene Rv0386 from Mycobacterium tuberculosis codes for an adenylyl cyclase catalytic domain fused to an AAA-ATPase and a helix-turn-helix DNA-binding domain. In Rv0386, the standard substrate, adenine-defining lysine-aspartate couple is replaced by glutamine-asparagine. The recombinant adenylyl cyclase domain was active with a V(max) of 8 nmol cAMP.mg(-1).min(-1). Unusual for adenylyl cyclases, Rv0386 displayed 20% guanylyl cyclase side-activity with GTP as a substrate. Mutation of the glutamine-asparagine pair either to alanine residues or to the canonical lysine-aspartate consensus abolished activity. This argues for a novel mechanism of substrate selection which depends on two non-canonical residues. Data from individual and coordinated point mutations suggest a model for purine definition based on an amide switch related to that previously identified in cyclic nucleotide phosphodiesterases.
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PMID:Adenylyl cyclase Rv0386 from Mycobacterium tuberculosis H37Rv uses a novel mode for substrate selection. 1595 67

In this study, we demonstrate that the subcellular localization of the mineralocorticoid receptor (MR) is regulated by tetratricopeptide domain (TPR) proteins. The high-molecular-weight immunophilin (IMM) FKBP52 links the MR-hsp90 complex to dynein/dynactin motors favoring the cytoplasmic transport of MR to the nucleus. Replacement of this hsp90-binding IMM by FKBP51 or the TPR peptide favored the cytoplasmic localization of MR. The complete movement machinery, including dynein and tubulin, could be recovered from paclitaxel/GTP-stabilized cytosol and was fully reassembled on stripped MR immune pellets. The whole MR-hsp90-based heterocomplex was transiently recovered in the soluble fraction of the nucleus after 10 min of incubation with aldosterone. Moreover, cross-linked MR-hsp90 heterocomplexes accumulated in the nucleus in a hormone-dependent manner, demonstrating that the heterocomplex can pass undissociated through the nuclear pore. On the other hand, a peptide that comprises the DNA-binding domain of MR impaired the nuclear export of MR, suggesting the involvement of this domain in the process. This study represents the first report describing the entire molecular system that commands MR nucleocytoplasmic trafficking and proposes that the MR-hsp90-TPR protein heterocomplex is dissociated in the nucleus rather than in the cytoplasm.
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PMID:The hsp90-FKBP52 complex links the mineralocorticoid receptor to motor proteins and persists bound to the receptor in early nuclear events. 2003 33

Guanosine triphosphate (GTP) binding and hydrolysis events often act as molecular switches in proteins, modulating conformational changes between active and inactive states in many signaling molecules and transport systems. The P element transposase of Drosophila melanogaster requires GTP binding to proceed along its reaction pathway, following initial site-specific DNA binding. GTP binding is unique to P elements and may represent a novel form of transpositional regulation, allowing the bound transposase to find a second site, looping the transposon DNA for strand cleavage and excision. The GTP-binding activity has been previously mapped to the central portion of the transposase protein; however, the P element transposase contains little sequence identity with known GTP-binding folds. To identify soluble, active transposase domains, a GFP solubility screen was used testing the solubility of random P element gene fragments in E. coli. The screen produced a single clone spanning known GTP-binding residues in the central portion of the transposase coding region. This clone, amino acids 275-409 in the P element transposase, was soluble, highly expressed in E.coli and active for GTP-binding activity, therefore is a candidate for future biochemical and structural studies. In addition, the chimeric screen revealed a minimal N-terminal THAP DNA-binding domain attached to an extended leucine zipper coiled-coil dimerization domain in the P element transposase, precisely delineating the DNA-binding and dimerization activities on the primary sequence. This study highlights the use of a GFP-based solubility screen on a large multidomain protein to identify highly expressed, soluble truncated domain subregions.
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PMID:A green fluorescent protein solubility screen in E. coli reveals domain boundaries of the GTP-binding domain in the P element transposase. 2084 11