Abstract
AbstractCytosolic sulfotransferases (SULTs) catalyze the transfer of a sulfonate group from the cofactor 3’-phosphoadenosine 5’-phosphosulfate to a hydroxyl (OH) containing substrate and play a critical role in the homeostasis of endogenous compounds, including hormones, neurotransmitters, and bile acids. In human, SULT2A1 sulfonates the 3-OH of bile acids; however, bile acid metabolism in mouse is dependent on a 7α-OH sulfonating SULT2A8 via unknown molecular mechanisms. In this study, the crystal structure of SULT2A8 in complex with adenosine 3’,5’-diphosphate and cholic acid was resolved at a resolution of 2.5 Å. Structural comparison with human SULT2A1 reveals different conformations of substrate binding loops. In addition, SULT2A8 possesses a unique substrate binding mode that positions the target 7α-OH of the bile acid close to the catalytic site. Furthermore, mapping of the critical residues by mutagenesis and enzyme activity assays further highlighted the importance of Lys44 and His48 for enzyme catalysis and Glu237 in loop 3 on substrate binding and stabilization. In addition, limited proteolysis and thermal shift assays suggested that the cofactor and substrates have protective roles in stabilizing SULT2A8 protein. Together, the findings unveil the structural basis of bile acid sulfonation targeting 7α-OH and shed light on the functional diversity of bile acid metabolism across species.
Highlights
IntroductionSulfonation involves the transfer of a sulfonate (SO3−) group from the universal cofactor 3’-phosphoadenosine-5’-phosphosulfate (PAPS) to a hydroxyl (OH) group of the substrate to generate a sulfonated product [18,19,20]
Supplementary key words bile acid metabolism protein structure homeostasis liver sulfotransferase mSULT2A8 X-ray crystallography 7-hydroxyl sulfonation
Full-length His-tagged SULT2A8 was cocrystallized with adenosine 3’ (PAP) or both PAP and Na sodium chenodeoxycholate (CDC); the crystals were only diffracted to resolutions of 3.6 and 7.9 Å, respectively
Summary
Sulfonation involves the transfer of a sulfonate (SO3−) group from the universal cofactor 3’-phosphoadenosine-5’-phosphosulfate (PAPS) to a hydroxyl (OH) group of the substrate to generate a sulfonated product [18,19,20] Based on their amino acid sequence similarities, mammalian cytosolic SULTs are classified into six families (SULT1-SULT6), of which SULT1 and SULT2 are the largest and most important families for xenobiotic and endobiotic metabolism [21]. Previous investigation of the bile acid pool in mouse shows that 7-OH bile acidmonosulfates were the predominant forms, and their levels are higher in males than in females [35, 39, 40] This contradicts with the hepatic mRNA expression pattern of Sult2a1, which was exclusively detected in female mice [38], indicating that sulfonation of bile acids at 7-OH requires another SULT.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
