Nucleotide binding and sulfation catalyzed by phenol sulfotransferase

Area of Science:

• Biochemistry
• Molecular Biology
• Enzymology

Background:

• Sulfation is crucial for biological sulfuryl group transfer.
• Sulfotransferases utilize adenosine 3',5'-bisphosphate (PAP) and 3'-phospho adenosine 5'-phosphosulfate (PAPS).
• Phenol sulfotransferase (PST) is an enzyme involved in sulfation.

Purpose of the Study:

• Investigate nucleotide binding and potential roles as cofactors/cosubstrates for PST.
• Identify novel substrates and reaction products of PST-catalyzed sulfation.
• Characterize the kinetics of PST with identified nucleotide substrates.

Main Methods:

• Binding studies to determine dissociation constants (K(d)) for various nucleotides.
• Enzymatic assays using 4-nitrophenyl sulfate as the sulfuryl donor.
• Spectrophotometry, High-Performance Liquid Chromatography (HPLC), and 31P Nuclear Magnetic Resonance ((31)P NMR) for activity determination and product identification.

Main Results:

• Ribose, adenine, and various nucleotides exhibit tight binding to PST.
• Adenosine 5'-monophosphate (AMP), adenosine 2',5'-bisphosphate (2',5'-PAP), and adenosine 2':3'-cyclic phosphate 5'-phosphate (2':3'-cyclic PAP) were identified as novel substrates.
• These nucleotides are sulfated at the 5'-phospho position by PST.
• Kinetic parameters (V(max) and K(m)) were determined for PST with these novel substrates.

Conclusions:

• PST demonstrates broader substrate specificity than previously known, binding and potentially sulfating various nucleotides.
• The discovery of novel nucleotide substrates and their 5'-phospho sulfation by PST opens new avenues for research.
• The physiological relevance of these findings regarding nucleotide binding and sulfation by PST requires further investigation.