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J Biol Chem. 2018 Apr 20;293(16):5781-5792. doi: 10.1074/jbc.RA117.001289. Epub 2018 Mar 7.

Structural basis for the regulatory interaction of the methylglyoxal synthase MgsA with the carbon flux regulator Crh in Bacillus subtilis.

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From the Departments of Molecular Structural Biology and
General Microbiology, GZMB, Georg-August-University Göttingen, 37077 Göttingen, Germany.
From the Departments of Molecular Structural Biology and.
the Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany, and.
the Bioanalytics Group, Institute for Clinical Chemistry, University Medical Center Göttingen, 37075 Göttingen, Germany.
General Microbiology, GZMB, Georg-August-University Göttingen, 37077 Göttingen, Germany,


Utilization of energy-rich carbon sources such as glucose is fundamental to the evolutionary success of bacteria. Glucose can be catabolized via glycolysis for feeding the intermediary metabolism. The methylglyoxal synthase MgsA produces methylglyoxal from the glycolytic intermediate dihydroxyacetone phosphate. Methylglyoxal is toxic, requiring stringent regulation of MgsA activity. In the Gram-positive bacterium Bacillus subtilis, an interaction with the phosphoprotein Crh controls MgsA activity. In the absence of preferred carbon sources, Crh is present in the nonphosphorylated state and binds to and thereby inhibits MgsA. To better understand the mechanism of regulation of MgsA, here we performed biochemical and structural analyses of B. subtilis MgsA and of its interaction with Crh. Our results indicated that MgsA forms a hexamer (i.e. a trimer of dimers) in the crystal structure, whereas it seems to exist in an equilibrium between a dimer and hexamer in solution. In the hexamer, two alternative dimers could be distinguished, but only one appeared to prevail in solution. Further analysis strongly suggested that the hexamer is the biologically active form. In vitro cross-linking studies revealed that Crh interacts with the N-terminal helices of MgsA and that the Crh-MgsA binding inactivates MgsA by distorting and thereby blocking its active site. In summary, our results indicate that dimeric and hexameric MgsA species exist in an equilibrium in solution, that the hexameric species is the active form, and that binding to Crh deforms and blocks the active site in MgsA.


Bacillus; Crh; HPr; bacteria; bacterial genetics; bacterial metabolism; catabolite regulation; crystal structure; glucose catabolism; glycolysis; metabolic regulation; methylglyoxal synthase; methylglyoxal toxicity; phosphoprotein; prokaryotic signal-transduction; protein cross-linking; protein structure; protein-protein interaction

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