Crystal structure of human catecholamine sulfotransferase

Area of Science:

• Biochemistry
• Structural Biology
• Enzymology

Background:

• Sulfonation is a key post-translational modification impacting biological molecule activity.
• Sulfotransferase enzymes (SULTs) catalyze sulfonation of diverse substrates, including neurotransmitters, hormones, and drugs.
• SULT1A3 specifically targets catecholamines like dopamine, adrenaline, and noradrenaline.

Purpose of the Study:

• To determine the crystal structure of SULT1A3.
• To investigate the structural basis for SULT1A3 activity and substrate specificity.
• To compare the active site structure of SULT1A3 with other sulfotransferases.

Main Methods:

• X-ray crystallography was used to determine the 2.4 Å resolution crystal structure of SULT1A3 with a bound sulfate.
• Structural comparisons were made with related sulfotransferase enzymes.

Main Results:

• The crystal structure of SULT1A3 reveals a core alpha/beta fold similar to estrogen and heparan sulfotransferases.
• Significant differences were observed in and around the active site, with several regions, including a 40-residue segment, being disordered.
• These disordered regions correspond to substrate and cofactor binding sites in other sulfotransferases.

Conclusions:

• The flexibility of SULT1A3's active site, characterized by disordered regions, suggests a disorder-order transition upon ligand binding.
• This dynamic flexibility may contribute to the broad substrate specificity observed for sulfotransferase enzymes.
• Understanding these structural dynamics provides insights into enzyme-substrate interactions and catalytic mechanisms.