Structural basis for dolichylphosphate mannose biosynthesis.

Area of Science:

• Biochemistry
• Structural Biology
• Molecular Biology

Background:

• Protein glycosylation is a vital post-translational modification essential for cellular function.
• Dolichylphosphate mannose (Dol-P-Man) is a key lipid-linked oligosaccharide precursor required for N-linked glycosylation and GPI anchor synthesis in eukaryotes and archaea.
• Dolichylphosphate mannose synthase (DPMS) catalyzes the formation of Dol-P-Man from GDP-mannose and dolichyl phosphate.

Purpose of the Study:

• To elucidate the structural mechanisms underlying Dol-P-Man synthesis by DPMS.
• To provide high-resolution structural insights into the catalytic cycle of archaeal DPMS.
• To rationalize the molecular basis of human congenital disorders of glycosylation (CDG) linked to DPMS dysfunction.

Main Methods:

• High-resolution X-ray crystallography of archaeal DPMS from Pyrococcus furiosus.
• Co-crystallization with nucleotide, GDP-mannose donor, and dolichylphosphate product analogs.
• Structural analysis of enzyme-substrate and enzyme-product complexes.

Main Results:

• Three high-resolution crystal structures of Pyrococcus furiosus DPMS were determined.
• Structures captured distinct states of the catalytic cycle, revealing dynamic interactions between lipid binding, metal ions, and protein loops.
• The findings illustrate how substrate binding and product release are coupled to conformational changes essential for catalysis.
• Structural data rationalize mutations in human DPMS (encoded by DPM1) associated with CDG.

Conclusions:

• The crystal structures provide unprecedented atomic-level detail of the DPMS catalytic mechanism.
• Understanding DPMS structure-function relationships is critical for deciphering glycosylation pathways and associated human diseases.
• These insights pave the way for potential therapeutic strategies targeting glycosylation disorders.