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Combinatorial active‐site variants confer sustained clavulanate resistance in BlaC β‐lactamase from Mycobacterium tuberculosis
Bacterial resistance to β‐lactam antibiotics is a global issue threatening the success of infectious disease treatments worldwide. Mycobacterium tuberculosis has been particularly resilient to
Multiple Conformers in Active Site of Human Dihydrofolate Reductase F31R/Q35E Double Mutant Suggest Structural Basis for Methotrexate Resistance*
TLDR
It is demonstrated that the important decrease of methotrexate affinity in variant F31R/Q35E is a result of synergistic effects of the combined substitutions, and the multiple conformers of Arg-31 further suggest that the amino acid substitutions may decrease the isomerization step required for tight binding of metotrexate.
Novel crystallization conditions for tandem variant R67 DHFR yield a wild-type crystal structure.
TLDR
A tandem dimer construct was created that linked two monomeric R67 DHFR subunits together and mutated the sequence of residues 66-69 of the first subunit from VQIY to INSF, and it was demonstrated that the variant protomer was selectively degraded by chymotrypsin, although no canonical chymosynthesis site had been introduced by these mutations.
Increasing methotrexate resistance by combination of active-site mutations in human dihydrofolate reductase.
TLDR
The MTX-resistant hDHFRs can protect eukaryotic cells from MTX toxicity by transfecting the most resistant mutants into DHFR-knock-out CHO cells, and offer potential for myeloprotection during administration of MTX in cancer treatment.
Mutational 'hot-spots' in mammalian, bacterial and protozoal dihydrofolate reductases associated with antifolate resistance: sequence and structural comparison.
TLDR
A comparative review of antifolate binding in diverse species provides new insights into the relationship between antifolates design and the development of mutational resistance and presents avenues for designing antIfolate-resistant mammalian DHFRs as chemoprotective agents.
2-Tier Bacterial and In Vitro Selection of Active and Methotrexate-Resistant Variants of Human Dihydrofolate Reductase
TLDR
A rapid and reliable 2-tier selection and screen for detection of activity as well as drug-resistance in mutated variants of a clinically-relevant drug-target enzyme will provide new insights into interactions between ligands and active-site residues of this clinically relevant human enzyme.
Asymmetric mutations in the tetrameric R67 dihydrofolate reductase reveal high tolerance to active‐site substitutions
TLDR
The results suggest that the presence of two native protomers in the R67 DHFR tetramer is sufficient to provide native‐like catalytic rate and thus ensure cellular proliferation, and suggests a high tolerance for active‐site substitutions.
Selectively weakened binding of methotrexate by human dihydrofolate reductase allows rapid ex vivo selection of mammalian cells
TLDR
It is demonstrated that bacterial selection of highly antifolate‐resistant hDHFR variants can provide selectable markers for rapid ex vivo enrichment of hematopoietic cells.
Modifying Enzyme Specificity by COmbinatorial Active Site Mutations
Recent developments in molecular biology offer new approaches for improving our understanding of enzyme-ligand interactions. The complexity of enzyme catalysis, consisting of ligand recognition and