ModG: Difference between revisions
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<StructureSection load='1atg' size='350' side='right' caption='Molybdate-binding protein complex with tungstate, ethylene glycol, acetate and sulfate (PDB entry [[1atg]])' scene=''> | |||
__TOC__ | __TOC__ | ||
=Introduction to ModG= | =Introduction to ModG= | ||
ModG is a cytoplasmic molybdate-binding protein exclusive to the aerobic nitrogen-fixer ''Azobacter vinelandii''.<ref name="MODGR1">PMID:11352591</ref> Molybdate is a molybdenum oxyanion (MoO42-). The group 6 element molybdenum is required by many enzymes that catalyze reactions associated with carbon, nitrogen, or sulfur metabolism.<ref name="MODGR2">PMID:21454640</ref> It is also part of the cofactor of the molybdoenzyme ModG. Not surprisingly, studies have linked ModG to molybdenum homeostasis within the cell.<ref name="MODGR1"/> | '''ModG''' is a cytoplasmic molybdate-binding protein exclusive to the aerobic nitrogen-fixer ''Azobacter vinelandii''.<ref name="MODGR1">PMID:11352591</ref> Molybdate is a molybdenum oxyanion (MoO42-). The group 6 element molybdenum is required by many enzymes that catalyze reactions associated with carbon, nitrogen, or sulfur metabolism.<ref name="MODGR2">PMID:21454640</ref> It is also part of the cofactor of the molybdoenzyme ModG. Not surprisingly, studies have linked ModG to molybdenum homeostasis within the cell.<ref name="MODGR1"/> | ||
=Structure= | =Structure= | ||
The molybdoenzyme is a homotrimer.<ref name="MODGR1"/> It can bind up to 8 molybdate molecules between 4 different types of <scene name='Sandbox_Reserved_306/1h9j/4'>active sites</scene> on subunit interfaces (BS1, BS1’, BS2, and BS2’). Binding site 1 and binding site 2 are found at opposite ends of the protein; binding site 1’ and binding site 2’ are found off-axis near like ends.<ref name="MODGR3">PMID:9862806</ref> The sites are connected by hydrogen bonds and thus a cooperative binding mechanism has been proposed for ModG whereby ligand engagement with type 2 sites induces conformational changes to asparagine residues at type 1 sites, reading the site for ligand interactions.<ref name="MODGR4">PMID:7665518</ref> The structure of ModG was solved by Delarbe et al. using multi-wavelength anomalous dispersion (MAD).<ref name="MODGR5"/> Crystallization required salt-free conditions established with polyethylene glycol (PEG), at which point the authors solved the PEG crystal form using molecular replacement.<ref name="MODGR5"/> | The molybdoenzyme is a homotrimer.<ref name="MODGR1"/> It can bind up to 8 molybdate molecules between 4 different types of <scene name='Sandbox_Reserved_306/1h9j/4'>active sites</scene> on subunit interfaces (BS1, BS1’, BS2, and BS2’). Binding site 1 and binding site 2 are found at opposite ends of the protein; binding site 1’ and binding site 2’ are found off-axis near like ends.<ref name="MODGR3">PMID:9862806</ref> The sites are connected by hydrogen bonds and thus a cooperative binding mechanism has been proposed for ModG whereby ligand engagement with type 2 sites induces conformational changes to asparagine residues at type 1 sites, reading the site for ligand interactions.<ref name="MODGR4">PMID:7665518</ref> The structure of ModG was solved by Delarbe et al. using multi-wavelength anomalous dispersion (MAD).<ref name="MODGR5"/> Crystallization required salt-free conditions established with polyethylene glycol (PEG), at which point the authors solved the PEG crystal form using molecular replacement.<ref name="MODGR5"/> | ||
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=Fate= | =Fate= | ||
ModG is eventually degraded and incorporated into molybdopterin, a cofactor of molybdenum enzymes, or the iron-molybdenum cofactor of a nitrogenase enzyme.<ref name="MODGR1"/><ref name="MODGR2"/> Currently there is little known about cofactor biosynthesis involving the ModG protein.<ref name="MODGR1"/> | ModG is eventually degraded and incorporated into molybdopterin, a cofactor of molybdenum enzymes, or the iron-molybdenum cofactor of a nitrogenase enzyme.<ref name="MODGR1"/><ref name="MODGR2"/> Currently there is little known about cofactor biosynthesis involving the ModG protein.<ref name="MODGR1"/> | ||
</StructureSection> | |||
=3D structures of ModG= | |||
[[1h9j]] – AvModG + phosphate + molybdate – ''Azotobacter vinelandii''<br /> | |||
[[1atg]] – AvModG + tungstate + sulfate + acetate<br /> | |||
[[1h9k]] - AvModG + tungstate + phosphate<br /> | |||
[[1h9m]] - AvModG + molybdate | |||
=References= | =References= | ||
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=See also= | =See also= | ||
[[Category:Molybdenum-containing enzyme]] | [[Category:Molybdenum-containing enzyme]] | ||
[[Category:Topic Page]] | |||
This page originally authored by Corbin Black | This page originally authored by Corbin Black | ||
