Journal:IUCrJ:S2052252519005372
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<b>Molecular Tour</b><br> | <b>Molecular Tour</b><br> | ||
| - | When facing nitrogen-limiting conditions, mycobacteria accumulate glucosylglycerate, which is rapidly mobilized when nitrogen levels are restored. In Mycolicibacterium hassiacum (basonym Mycobacterium hassiacum), glucosylglycerate mobilization was concomitant with the up-regulation of the gene coding for glucosylglycerate hydrolase (GgH). Highly conserved among unrelated phyla, GgH is able to hydrolyse glucosylglycerate to glycerate and glucose and is likely involved in bacterial reactivation following nitrogen starvation. | + | When facing nitrogen-limiting conditions, mycobacteria accumulate glucosylglycerate, which is rapidly mobilized when nitrogen levels are restored. In ''Mycolicibacterium hassiacum'' (basonym ''Mycobacterium hassiacum''), glucosylglycerate mobilization was concomitant with the up-regulation of the gene coding for glucosylglycerate hydrolase (GgH). Highly conserved among unrelated phyla, GgH is able to hydrolyse glucosylglycerate to glycerate and glucose and is likely involved in bacterial reactivation following nitrogen starvation. |
Using X-ray crystallography, high-resolution structural models of different forms of GgH could be obtained. These detailed views of GgH revealed several important aspects of its mode of action, including its oligomeric organization, with the homotetramer present in the crystals being fully compatible with the architecture of the active form of GgH in solution, assessed by small-angle X-ray scattering (SAXS) using synchrotron radiation. The crystallographic structures of unliganded and substrate-bound GgH further revealed the existence of a coordinated movement of several surface loops in the vicinity of the active site during the catalytic cycle of the enzyme. Therefore, the active site of GgH is only completely structured upon substrate binding, with the mobile loops shielding the bound compounds from the solvent and facilitating the enzymatic reaction. Reversal of this movement opens up the active site of GgH, allowing product release and readying the enzyme for another catalytic cycle. | Using X-ray crystallography, high-resolution structural models of different forms of GgH could be obtained. These detailed views of GgH revealed several important aspects of its mode of action, including its oligomeric organization, with the homotetramer present in the crystals being fully compatible with the architecture of the active form of GgH in solution, assessed by small-angle X-ray scattering (SAXS) using synchrotron radiation. The crystallographic structures of unliganded and substrate-bound GgH further revealed the existence of a coordinated movement of several surface loops in the vicinity of the active site during the catalytic cycle of the enzyme. Therefore, the active site of GgH is only completely structured upon substrate binding, with the mobile loops shielding the bound compounds from the solvent and facilitating the enzymatic reaction. Reversal of this movement opens up the active site of GgH, allowing product release and readying the enzyme for another catalytic cycle. | ||
Finally, the different complexes of GgH with substrates and substrate analogues allowed to infer the molecular details of the reaction mechanism of this inverting hydrolase and to ascribe the functional roles of highly conserved residues in this class of enzymes. | Finally, the different complexes of GgH with substrates and substrate analogues allowed to infer the molecular details of the reaction mechanism of this inverting hydrolase and to ascribe the functional roles of highly conserved residues in this class of enzymes. | ||
Revision as of 10:30, 30 April 2019
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This page complements a publication in scientific journals and is one of the Proteopedia's Interactive 3D Complement pages. For aditional details please see I3DC.
