Sandbox Reserved 1094
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==Glucose-6-Phosphate Dehydrogenase from Leuconostoc ''mesenteroides''== | ==Glucose-6-Phosphate Dehydrogenase from Leuconostoc ''mesenteroides''== | ||
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The protein''' Glucose-6-Phosphate Dehydrogenase''' is an enzyme involved in the metabolic pathways of the majority of organisms. Leuconostoc ''mesenteroides'' is a Bacilli <font color='purple'>Gram-positive</font> bacterium that expresses this enzyme. | The protein''' Glucose-6-Phosphate Dehydrogenase''' is an enzyme involved in the metabolic pathways of the majority of organisms. Leuconostoc ''mesenteroides'' is a Bacilli <font color='purple'>Gram-positive</font> bacterium that expresses this enzyme. | ||
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== Structural highlights == | == Structural highlights == | ||
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Glucose-6-Phosphate Dehydrogenase is formed of a homodimer, so a dimer of two identical [https://en.wikipedia.org/wiki/Protein_subunit subunit]. | Glucose-6-Phosphate Dehydrogenase is formed of a homodimer, so a dimer of two identical [https://en.wikipedia.org/wiki/Protein_subunit subunit]. | ||
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Glucose-6-Phosphate Dehydrogenase from Leuconostoc mesenteroides
The protein Glucose-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.
Function
G6PD plays an important role in the metabolism of L.mesenteroides. L.mesenteroides is a facultactively anaerobic micro-organism which metabolizes glucose to generate lactic acid, ethanol but also carbon dioxyde. This glucose metabolic process (glycolysis and pentose phosphate pathway) is catalysed by G6PD. During this process, NADH is synthesised and used in the heterolactic fermentation and the biosynthesis of fatty acids. The protein G6PD 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]. It has in total 2 chains. In the link below, these two chains are represented by one unique sequence entity.
External resource : click on [1] to see the graphical representation on the RCSB website.
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.
Check, as determined by ConSurfDB.
Mutations
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 a substitution of the bold amino acids by another one[5]:
MVSEIKTLVT FFGG T GDLAK R TK LYPSVFNL YKKGYLQKHF AIVGTA RQ AL NDDEFKQLVR DSIKDFTDDQ AQAEAFIEHF SYRAHDVTDA ASYAVLKEAI EEAADKFDID GNRIFYMSVA PRFFGTIAKY LKSEGLLADT GYNRLMIEK P FGTSYDTAAE LQNDLENAFD DNQLFRI DHY LG K EMVQNIA ALRFGNPIFD AAWNKDYIKN VQVTLSEVLG VEERAGYYDT AGALLDMIQN H TMQIVGWLA MEKPESFTDK DIRAAKNAAF NALKIYDEAE VNKYFVRAQY GAGDSADFKP YLEELDVPAD SKNNTFIAGE LQFDLPRWEG VPFYVRSGKR LAA K QTRVDI VFKAGTFNFG SEQEAQEAVL SIII D PKGAI ELKLNAKSVE DAFNTRTIDL GWTVSDEDKK NTPEP Y ERMI HDTMNGDGSN FADWNGVSIA WKFVDAISAV YTADKAPLET YKSGSMGPEA SDKLLAANGD AWVFKG.
This sequence being the normal protein sequence found in L. mesenteroides.
Structural highlights
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References
- ↑ 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
- ↑ GeneID:29577449
- ↑ 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:http://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
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DONATI Quentin, LOGEREAU Lucie, PROST Loana
