Mutagenesis inducing catalytic activity loss: +200 mutations have been identified. A change of amino acids leads to disruption of the normal
Mutagenesis of this enzyme induces catalytic activity loss: more than 200 mutations have been identified.
structure/function/reduce the expression of enzymes.
A mutation in a nucleotide in the sequence coding for G6PD leads to disruption of the normal expression of the enzyme, or to a disruption in the amino acid structure of the enzyme which leads to a loss or decrease of catalytic activity toward its substrate.
The most common mutations in the amino acids sequence found that induce a loss of catalytic activity are<ref>PMID: 11106479</ref>:
This sequence being the normal protein sequence found in L. ''mesenteroides''.
== Structural highlights ==
== Structural highlights ==
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The protein Glycose-6-Phosphate Dehydrogenase is an enzyme involved in the metabolic pathways of the majority of organisms. Leuconostoc mesenteroides is a Bacilli Gram-positive bacterium that expresses this enzyme.
The Glucose-6-Phosphate Dehydrogenase is involved in the processing of carbohydrates as it has important roles in the glucose metabolic process (glycolysis and pentose phosphate pathway).
It also has a role in protecting cells from destruction as it produces the co-factor NADPH which plays a role in protecting cells from reactive oxygen species [1].
Genomic context
It is coded by the G6PD gene (1461 nucleotides)[2].
Catalytic activity
D-glucose 6-phosphate + NAD+ → 6-phospho-D-glucono-1,5-lactone + H+ + NADH[3]
KM=114 µM for G6PD (with NADP), KM=69 µM for G6PD (with NAD),
KM=8.0 µM for NADP, KM=160 µM for NAD.
Its regulation depends on the concentration of substrate and coenzyme, rate limiting step in pentose phosphate pathway[4].
Optimum pH for its activity is 5.4 - 8.9.
Evolutionary conservation
The different structures conserved evolutionary can be observed according to the scale following.
Mutagenesis of this enzyme induces catalytic activity loss: more than 200 mutations have been identified.
A mutation in a nucleotide in the sequence coding for G6PD leads to disruption of the normal expression of the enzyme, or to a disruption in the amino acid structure of the enzyme which leads to a loss or decrease of catalytic activity toward its substrate.
The most common mutations in the amino acids sequence found that induce a loss of catalytic activity are[5]:
This sequence being the normal protein sequence found in L. mesenteroides.
Structural highlights
It is formed of a homodimer, so a dimer of two identical monomers[6]. Each monomer is composed of 2 domains, 1 red and 1 green.
Depending on several conditions, it can dimerize to form tetramers. Each monomer in the complex has a substrate binding site that binds to G6P, and a catalytic coenzyme binding site that binds to NADP+/NADPH using the Rossman fold.
↑Ravera S, Calzia D, Morelli A, Panfoli I. Oligomerization studies of Leuconostoc mesenteroides G6PD activity after SDS-PAGE and blotting. Mol Biol (Mosk). 2010 May-Jun;44(3):472-6. PMID:20608171
↑Cosgrove MS, Naylor C, Paludan S, Adams MJ, Levy HR. On the mechanism of the reaction catalyzed by glucose 6-phosphate dehydrogenase. Biochemistry. 1998 Mar 3;37(9):2759-67. PMID:9485426 doi:10.1021/bi972069y
↑Cosgrove MS, Loh SN, Ha JH, Levy HR. The catalytic mechanism of glucose 6-phosphate dehydrogenases: assignment and 1H NMR spectroscopy pH titration of the catalytic histidine residue in the 109 kDa Leuconostoc mesenteroides enzyme. Biochemistry. 2002 Jun 4;41(22):6939-45. doi: 10.1021/bi0255219. PMID:12033926 doi:https://dx.doi.org/10.1021/bi0255219
↑Vought V, Ciccone T, Davino MH, Fairbairn L, Lin Y, Cosgrove MS, Adams MJ, Levy HR. Delineation of the roles of amino acids involved in the catalytic functions of Leuconostoc mesenteroides glucose 6-phosphate dehydrogenase. Biochemistry. 2000 Dec 12;39(49):15012-21. PMID:11106479
↑Rowland P, Basak AK, Gover S, Levy HR, Adams MJ. The three-dimensional structure of glucose 6-phosphate dehydrogenase from Leuconostoc mesenteroides refined at 2.0 A resolution. Structure. 1994 Nov 15;2(11):1073-87. PMID:7881907
