Disease relevance of folA

• Peptide fragment studies on the folding elements of dihydrofolate reductase from Escherichia coli [1].
• In this report, the Mycobacterium avium folA gene was identified by functional genetic complementation, sequenced, and expressed for the first time [2].
• Nucleotide sequence reveals overlap between T4 phage genes encoding dihydrofolate reductase and thymidylate synthase [3].
• Simulations of hydride and deuteride transfer catalyzed by dihydrofolate reductase from the hyperthermophile Thermotoga maritima (TmDHFR) are presented [4].
• The properties of phage particles produced after infection of the nonpermissive host with the one known T4D mutant containing a nonsense mutation in its dfr gene suggested that these progeny particles contained a partial polypeptide, which was large enough to serve as a structural element [5].

High impact information on folA

• Sulfamethoxazole and other sulfa drugs are moderately potent inhibitors of Escherichia coli dihydrofolate reductase [6].
• Here lineages of active enzymes descended from the homotetrameric 78 residue dihydrofolate reductase (DHFR) encoded by the Escherichia coli R67 plasmid were generated by iterative RNA hypermutagenesis, resulting in >20% amino acid replacement [7].
• Eradication of the SD sequence in the absence of a DB abolished the translational activity of RBS fragments that were fused to a dihydrofolate reductase reporter gene [8].
• Neutron diffraction studies of Escherichia coli dihydrofolate reductase complexed with methotrexate [9].
• At the active site, the N1 atom of MTX is protonated and thus charged when bound to DHFR [9].

Chemical compound and disease context of folA

• Escherichia coli dihydrofolate reductase (DHFR; EC 1.5.1.3) contains five tryptophan residues that have been replaced with 6-19F-tryptophan [10].
• The refolding of Escherichia coli dihydrofolate reductase (EC 1.5.1.3), reversibly unfolded in 7 M urea, was monitored by the reappearance of enzyme activity after diluting the unfolded enzyme into low urea concentrations (less than or equal to 2 M) in the presence of substrates [11].
• Role of aspartate 27 in the binding of methotrexate to dihydrofolate reductase from Escherichia coli [12].
• Crystal structure of a novel trimethoprim-resistant dihydrofolate reductase specified in Escherichia coli by R-plasmid R67 [13].
• We have determined the pKa of N5 of dihydrofolate in the Escherichia coli DHFR/NADP+/H2folate ternary complex by Raman difference spectroscopy and found that the value is 6 [14].

Biological context of folA

• Binding sites in Escherichia coli dihydrofolate reductase communicate by modulating the conformational ensemble [15].
• The kinetics of refolding of Escherichia coli dihydrofolate reductase (EC 1.5.1.3) have been examined upon dilution of unfolded enzyme in 4.5 M urea to 1.29 M urea in 0.02 M phosphate buffer (pH 7.2) at 10 degrees C. Changes in the intrinsic protein fluorescence on refolding are characterized by four phases [16].
• Hypermutagenic PCR has been used to simulate pseudogene evolution of the Escherichia coli R67 dihydrofolate reductase gene [17].
• Halobacterium volcanii mutants that are resistant to the dihydrofolate reductase inhibitor trimethoprim contain DNA sequence amplifications [18].
• The Cryptococcus neoformans dihydrofolate reductase (DHFR) gene has been isolated from cDNA and genomic DNA libraries [19].

Anatomical context of folA

• Transfected E. coli folA dhfr could complement the lack of endogenous DHFR in Chinese hamster ovary (CHO) cells lacking a functional dhfr gene [20].
• Ricin A chain can transport unfolded dihydrofolate reductase into the cytosol [21].
• Here we show that removal of as few as 4 amino-terminal residues from the subunit IV presequence (which had been attached to the cytosolic protein dihydrofolate reductase) blocks import of the protein into mitochondria and proteolytic removal of the presequence by the soluble matrix protease [22].
• A 29 base pair fragment of its ribosome binding site containing the initiation triplet, the Shine-Dalgarno sequence (S-D), 10 nucleotides (nt) upstream and 6 nt downstream of these central elements was cloned into a vector to control the expression of the mouse dihydrofolate reductase gene (dhfr) [23].
• Mouse fibroblast NIH3T3 cells infected with DC/SV6S31 GPT are more resistant to MTX than cells infected with DC/SV6S31, which carries the Serine 31 DHFR and the neomycin resistance gene cDNA [24].

Associations of folA with chemical compounds

• In contrast to plasmid-derived bacterial dhfr genes previously used as selection markers in mammalian cells, the folA gene product is inhibitable by methotrexate (MTX) and trimethoprim (TMP) [20].
• Dihydrofolate reductase (DHFR) catalyzes the reduction of dihydrofolate to tetrahydrofolate [25].
• Vibrational structure of dihydrofolate bound to R67 dihydrofolate reductase [26].
• Inhibition of thymidylate synthetase and dihydrofolate reductase by naturally occurring oligoglutamate derivatives of folic acid [27].
• We further assessed the chloroplast-targeting ability of the NH2-terminal 48 amino acids by fusing to the foreign protein, mouse dihydrofolate reductase (DHFR) [28].

Other interactions of folA

• A thyA mutation accompanied the fol deletion and is required for survival of a dihydrofolate reductase-deficient strain [29].
• Most notably, the specific activity of the dihydrofolate reductase formed in the presence of the substrate dihydrofolate was increased and this effect was specific for dihydrofolate reductase since it was not observed with other proteins synthesised in the same system [30].

Analytical, diagnostic and therapeutic context of folA

• Complementation tests indicated that the conditional folA deficiency was a cis effect of transcription from the tac promoter, perhaps due to head-to-head collision between converging RNA polymerases [31].
• Gel-filtration analysis of purified DHFR confirmed that, in vitro, the protein was a monomer in the absence of dimerizer drug; in the presence of bisMTX, a complex of twice the monomeric molecular weight was observed [32].
• Probing the functional role of phenylalanine-31 of Escherichia coli dihydrofolate reductase by site-directed mutagenesis [33].
• An expedient and facile one-step synthesis of a biguanide library by microwave irradiation coupled with simple product filtration. Inhibitors of dihydrofolate reductase [34].
• Determination by Raman spectroscopy of the pKa of N5 of dihydrofolate bound to dihydrofolate reductase: mechanistic implications [14].

References