MESH1 functions as a metazoan PAPS phosphatase to regulate sulfation

Area of Science:

• Biochemistry
• Molecular Biology
• Structural Biology

Background:

• Biological sulfation relies on 3'-phosphoadenosine-5'-phosphosulfate (PAPS) as the universal sulfate donor.
• The PAPS biosynthetic pathway is known, but the enzyme responsible for PAPS degradation (a PAPS phosphatase) remained elusive.

Purpose of the Study:

• To identify and characterize the PAPS phosphatase involved in regulating PAPS levels.
• To elucidate the structural and functional roles of MESH1 in PAPS metabolism and sulfation homeostasis.

Main Methods:

• Biochemical assays to confirm MESH1's PAPS phosphatase activity.
• Crystallographic analysis of the MESH1-PAPS complex.
• Cellular localization studies (Golgi).
• In vitro knockdown and knockout studies in cell lines and animal models (brachymorphic mice, C. elegans).

Main Results:

• MESH1 was identified as a PAPS phosphatase, hydrolyzing PAPS to adenosine-5'-phosphosulfate and phosphate.
• Structural analysis confirmed PAPS as a substrate for MESH1.
• MESH1 localizes to the Golgi, the site of sulfated glycosaminoglycan (sGAG) synthesis.
• MESH1 knockdown enhanced sGAG production; Mesh1 knockout in mice increased sGAG levels and bone density.
• MESH1 overexpression alleviated neurotoxicity in C. elegans by reducing PAPS levels.

Conclusions:

• MESH1 is a key PAPS phosphatase regulating PAPS homeostasis.
• MESH1 plays a significant role in sulfation, particularly in sGAG production.
• MESH1 represents a potential therapeutic target for conditions associated with sulfation deficiencies.