8BC4

Cryo-EM Structure of a BmSF-TAL - Sulfofructose Schiff Base Complex in symmetry group C1

Summary for 8BC4

• Entry DOI: 10.2210/pdb8bc4/pdb
• EMDB information: 15962
• Descriptor: Transaldolase, (2~{R},3~{S},4~{S})-2,3,4,6-tetrakis(oxidanyl)hexane-1-sulfonic acid (3 entities in total)
• Functional Keywords: transaldolase, sulfofructose, cryo-em, decamer, transferase
• Biological source: Bacillus aryabhattai
• Total number of polymer chains: 10
• Total formula weight: 247788.86

Authors

Snow, A.J.D.,Sharma, M.,Blaza, J.,Davies, G.J. (deposition date: 2022-10-14, release date: 2023-01-18, Last modification date: 2024-11-20)

Primary citation

Snow, A.J.D.,Sharma, M.,Abayakoon, P.,Williams, S.J.,Blaza, J.N.,Davies, G.J.
Structure and mechanism of sulfofructose transaldolase, a key enzyme in sulfoquinovose metabolism.
Structure, 31:244-, 2023

PubMed Abstract: Sulfoquinovose (SQ) is a key component of plant sulfolipids (sulfoquinovosyl diacylglycerols) and a major environmental reservoir of biological sulfur. Breakdown of SQ is achieved by bacteria through the pathways of sulfoglycolysis. The sulfoglycolytic sulfofructose transaldolase (sulfo-SFT) pathway is used by gut-resident firmicutes and soil saprophytes. After isomerization of SQ to sulfofructose (SF), the namesake enzyme catalyzes the transaldol reaction of SF transferring dihydroxyacetone to 3C/4C acceptors to give sulfolactaldehyde and fructose-6-phosphate or sedoheptulose-7-phosphate. We report the 3D cryo-EM structure of SF transaldolase from Bacillus megaterium in apo and ligand bound forms, revealing a decameric structure formed from two pentameric rings of the protomer. We demonstrate a covalent "Schiff base" intermediate formed by reaction of SF with Lys89 within a conserved Asp-Lys-Glu catalytic triad and defined by an Arg-Trp-Arg sulfonate recognition triad. The structural characterization of the signature enzyme of the sulfo-SFT pathway provides key insights into molecular recognition of the sulfonate group of sulfosugars.

PubMed: 36805128
DOI: 10.1016/j.str.2023.01.010

Experimental method

ELECTRON MICROSCOPY (2.7 Å)