Mannose-binding geometry of pradimicin A.

Area of Science:

• Natural Product Chemistry
• Glycobiology
• Structural Biology

Background:

• Pradimicins (PRMs) and benanomicins are non-peptidic natural products with lectin-like properties, recognizing D-mannopyranoside (Man) and exhibiting antifungal/anti-HIV activities.
• Their potential as therapeutic leads is hindered by an unestablished molecular basis for Man recognition, complicated by aggregation and dual binding sites.
• Understanding PRM-A's primary Man binding geometry is crucial for elucidating their glycan specificity.

Purpose of the Study:

• To investigate the precise geometry of D-mannopyranoside (Man) binding to the primary site of PRM-A.
• To elucidate the molecular basis of Man recognition and glycan specificity for Pradimicins (PRMs).
• To overcome analytical challenges posed by PRM aggregation and multiple binding sites.

Main Methods:

• Utilized a solid aggregate of a 1:1 complex of PRM-A and Man for analysis.
• Employed solid-state NMR spectroscopy to evaluate intermolecular distances between PRM-A and Man.
• Validated binding geometry through co-precipitation experiments using deoxy-mannopyranoside (Man) derivatives.

Main Results:

• Solid-state NMR revealed close contact between the C2-C4 region of Man and PRM-A's primary binding site.
• The C1 and C6 positions of Man were found to be relatively distant from the primary binding site.
• Co-precipitation experiments confirmed that PRM-A binds to both terminal and internal 6-substituted Man residues.

Conclusions:

• The study provides detailed insights into the molecular basis of D-mannopyranoside (Man) recognition by PRM-A.
• PRM-A exhibits specific binding to both terminal and internal mannose residues in glycans.
• These findings advance the understanding of Pradimicins' lectin mimicry and therapeutic potential.