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The Molecular Basis of Sulfosugar Selectivity in Sulfoglycolysis

preprint
revised on 23.09.2020 and posted on 23.09.2020 by Mahima Sharma, Palika Abayakoon, Yi Jin, Ruwan Epa, James P. Lingford, Tomohiro Shimada, Masahiro Nakano, Janice Mui, Akira Ishihama, Ethan D. Goddard-Borger, Gideon J. Davies, Spencer Williams
The sulfosugar sulfoquinovose (SQ) is produced by essentially all photosynthetic organisms on earth and is metabolized bacteria through the process of sulfoglycolysis. The sulfoglycolytic Embden-Meyerhof-Parnas pathway metabolises SQ to produce dihydroxyacetone phosphate and sulfolactaldehyde and is analogous to the classical Embden-Meyerhof-Parnas glycolysis pathway for the metabolism of glucose-6-phosphate, though the former only provides one C3 fragment to central metabolism, with excretion of the other C3 fragment as dihydroxypropanesulfonate. Here, we report a comprehensive structural and biochemical analysis of the three core steps of sulfoglycolysis catalyzed by SQ isomerase, sulfofructose (SF) kinase and sulfofructose-1-phosphate aldolase. Our data shows that despite the superficial similarity of this pathway to glycolysis, the sulfoglycolytic enzymes are specific for SQ metabolites and are not catalytically active on related metabolites from glycolytic pathways. This observation is rationalized by 3D structures of each of these enzymes, which reveal the presence of conserved sulfonate-binding pockets. We show that SQ isomerase acts preferentially on the b-anomer of SQ and reversibly produces both SF and sulforhamnose (SR), a previously unknown sugar that acts as a transcriptional regulator for the transcriptional repressor CsqR that regulates SQ-utilisation. We also demonstrate that SF kinase is a key regulatory enzyme for the pathway that experiences complex allosteric modulation by the metabolites AMP, ADP, ATP, F6P, FBP, PEP, and citrate. This body of work provides fresh insights into the mechanism, specificity and regulation of sulfoglycolysis and has important implications for understanding how this biochemistry interfaces with central metabolism in prokaryotes to process this major repository of biogeochemical sulfur.

Funding

Australian Research Council DP180101957

Leverhulme Trust (RPG-2017-190)

MEXT Cooperative Research Program of Network Joint Research Center for Materials and Devices

National Health and Medical Research Council of Australia (GNT1139546 and GNT1139549)

History

Email Address of Submitting Author

sjwill@unimelb.edu.au

Institution

University of Melbourne

Country

Australia

ORCID For Submitting Author

0000-0001-6341-4364

Declaration of Conflict of Interest

no conflict of interest

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