Disease relevance of folA

• A 1.8-kb SalI-BamHI fragment which was able to confer methotrexate resistance in yeast also complemented an E. coli DHFR-deficient (folA) mutant [1].
• The dihydrofolate reductase structural gene, folA, has been closed into the multicopy vector pBR322 following the gene's enrichment by bacteriophage Mu-mediated transposition [2].
• Crystal structures of Escherichia coli and Lactobacillus casei dihydrofolate reductase refined at 1.7 A resolution. I. General features and binding of methotrexate [3].
• Species-specific irreversible inhibition of Neisseria gonorrhoeae dihydrofolate reductase by a substituted 2,4-diamino-5-benzylpyrimidine [4].
• The structure of the mutant dihydrofolate reductase from Streptococcus faecium. Amino acid sequence of peptide CNBr 7 and complete sequence of the protein [5].

High impact information on folA

• Methotrexate does not mask the presequence, but stabilizes the dihydrofolate reductase moiety [6].
• This suggests that dihydrofolate reductase must at least partly unfold in order to be transported across mitochondrial membranes [6].
• Functional role of aspartic acid-27 in dihydrofolate reductase revealed by mutagenesis [7].
• To study the environment of a preprotein as it crosses the plasma membrane of Escherichia coli, unique cysteinyl residues were introduced into proOmpA and the genes for these mutant preproteins were fused to the gene of dihydrofolate reductase (Dhfr) [8].
• 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

• Both MTX and TMP inhibited growth of E. coli folA dhfr-transfected CHO cells [10].
• A plasmid containing part of the csgD gene was isolated during a screen for multicopy suppressors of glycine auxotrophy caused by deleting the folA gene in E. coli [11].
• Suppression of a UGA mutation in the E. coli fol gene followed by N-terminal sequence analysis of purified dihydrofolate reductase showed that this tRNA was an efficient suppressor that inserted predominantly tryptophan [12].
• The apoenzyme of wild-type (WT) dihydrofolate reductase (DHRF) from Escherichia coli exists in two conformational states, Et and Ew, which differ in affinity for NADPH and in kinetic competence [13].
• Interconvertible forms of Escherichia coli dihydrofolate reductase with different affinities for analogs of dihydrofolate [14].

Biological context of folA

• Transfer of a plasmid containing the E. coli folA gene into atsR mutant cells of K. aerogenes resulted in repression of the arylsulfatase synthesis [15].
• Thus, we conclude that the folA gene codes a negative regulator for the ats operon [15].
• Directed mutagenesis of dihydrofolate reductase [16].
• Defining the role of active-site loop fluctuations in dihydrofolate reductase catalysis [17].
• Interaction of dihydrofolate reductase with methotrexate: ensemble and single-molecule kinetics [18].

Anatomical context of folA

• Nucleotide sequence analysis of a cDNA clone shown to direct the synthesis in Escherichia coli of a pI 6.5 form of dihydrofolate reductase (DHFR) with an apparent molecular weight of 21,000 has clarified the allelic nature of the DHFR genes present in the Chinese hamster lung cell line DC-3F [19].
• To examine the potential of ricin A to carry proteins into the cytosol and the requirement for unfolding of the passenger protein, we connected mouse dihydrofolate reductase (DHFR) to ricin A by gene fusion via a spacer peptide [20].
• The cleavage sites were estimated by determining the amino (N)-terminal amino acid sequences of dihydrofolate reductase-fused processed products purified partially by affinity chromatography from the lysates, indicating that cleavage occurred at sites identical to those observed in eukaryotic cells [21].
• A high proportion, about 20% of newly synthesized dihydrofolate reductase and about 50% of rhodanese, stayed with the ribosomes after coupled transcription/translation [22].
• The 206-amino acid P. carinii DHFR was expressed to high levels in Escherichia coli inclusion bodies using the T7 promoter expression system [23].

Associations of folA with chemical compounds

• Calculations for wild-type dihydrofolate reductase and a triple mutant, along with the associated single and double mutants, indicate that each enzyme system samples a unique distribution of coupled motions correlated to hydride transfer [24].
• Mammalian expression modules encoding the dominant marker neomycin phosphotransferase or the amplifiable dihydrofolate reductase gene expressed from SV40 promoters were inserted for use in gene transfer studies [25].
• DHFR was modified to permit the covalent addition of a fluorescent molecule, Alexa 488, and a biotin at the N terminus of the molecule [18].
• Three of the strains produced dihydrofolate reductase with an increased Ki value for trimethoprim [26].
• In the formation of the ternary complex with NADPH, trimethoprim bound to dihydrofolate reductase as if all the enzyme existed as a single species with a KD for trimethoprim of 1.9 nM [14].

Physical interactions of folA

• X-ray data have been extended to 1.7 A for a binary complex of Escherichia coli dihydrofolate reductase with methotrexate and a ternary complex of Lactobacillus casei dihydrofolate reductase with methotrexate and NADPH [3].

Other interactions of folA

• The close proximity of the E. coli kefC gene to the folA gene, encoding dihydrofolate reductase, has been utilized to clone the structural gene for the system from a Clarke-Carbon plasmid [27].
• Naturally occurring oligoglutamate derivatives of folic acid in extracts of Escherichia coli have been isolated on the basis of their inhibitory actions toward thymidylate synthetase and dihydrofolate reductase [28].

Analytical, diagnostic and therapeutic context of folA

• Three mutations of the enzyme dihydrofolate reductase were constructed by oligonucleotide-directed mutagenesis of the cloned Escherichia coli gene [16].
• The folding of Escherichia coli dihydrofolate reductase was examined at pH 7.8 and 15 degrees C by using stopped-flow fluorescence and absorbance spectroscopies [29].
• Neutron diffraction studies of Escherichia coli dihydrofolate reductase complexed with methotrexate [9].
• Effect of N-bromosuccinimide modification on dihydrofolate reductase from a methotrexate-resistant strain of Escherichia coli. Activity, spectrophotometric, fluorescence and circular dichroism studies [30].
• The DHFR/ligase derivative proteins were then efficiently purified by affinity chromatography [31].

References