Structural highlights
Function
ILVC_SLAES Involved in the biosynthesis of branched-chain amino acids (BCAA). Catalyzes an alkyl-migration followed by a ketol-acid reduction of (S)-2-acetolactate (S2AL) to yield (R)-2,3-dihydroxy-isovalerate. In the isomerase reaction, S2AL is rearranged via a Mg-dependent methyl migration to produce 3-hydroxy-3-methyl-2-ketobutyrate (HMKB). In the reductase reaction, this 2-ketoacid undergoes a metal-dependent reduction by NADPH to yield (R)-2,3-dihydroxy-isovalerate.[HAMAP-Rule:MF_00435][1]
Publication Abstract from PubMed
To date, efforts to switch the cofactor specificity of oxidoreductases from nicotinamide adenine dinucleotide phosphate (NADPH) to nicotinamide adenine dinucleotide (NADH) have been made on a case-by-case basis with varying degrees of success. Here we present a straightforward recipe for altering the cofactor specificity of a class of NADPH-dependent oxidoreductases, the ketol-acid reductoisomerases (KARIs). Combining previous results for an engineered NADH-dependent variant of Escherichia coli KARI with available KARI crystal structures and a comprehensive KARI-sequence alignment, we identified key cofactor specificity determinants and used this information to construct five KARIs with reversed cofactor preference. Additional directed evolution generated two enzymes having NADH-dependent catalytic efficiencies that are greater than the wild-type enzymes with NADPH. High-resolution structures of a wild-type/variant pair reveal the molecular basis of the cofactor switch.
General approach to reversing ketol-acid reductoisomerase cofactor dependence from NADPH to NADH.,Brinkmann-Chen S, Flock T, Cahn JK, Snow CD, Brustad EM, McIntosh JA, Meinhold P, Zhang L, Arnold FH Proc Natl Acad Sci U S A. 2013 Jul 2;110(27):10946-51. doi:, 10.1073/pnas.1306073110. Epub 2013 Jun 17. PMID:23776225[2]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Brinkmann-Chen S, Flock T, Cahn JK, Snow CD, Brustad EM, McIntosh JA, Meinhold P, Zhang L, Arnold FH. General approach to reversing ketol-acid reductoisomerase cofactor dependence from NADPH to NADH. Proc Natl Acad Sci U S A. 2013 Jul 2;110(27):10946-51. doi:, 10.1073/pnas.1306073110. Epub 2013 Jun 17. PMID:23776225 doi:10.1073/pnas.1306073110
- ↑ Brinkmann-Chen S, Flock T, Cahn JK, Snow CD, Brustad EM, McIntosh JA, Meinhold P, Zhang L, Arnold FH. General approach to reversing ketol-acid reductoisomerase cofactor dependence from NADPH to NADH. Proc Natl Acad Sci U S A. 2013 Jul 2;110(27):10946-51. doi:, 10.1073/pnas.1306073110. Epub 2013 Jun 17. PMID:23776225 doi:10.1073/pnas.1306073110
