The functional principle of eukaryotic molybdenum insertases.

Area of Science:

• Biochemistry
• Structural Biology
• Enzymology

Background:

• The molybdenum cofactor (Moco) is essential for numerous Moco-dependent enzymes critical for life.
• Moco biosynthesis involves multiple enzymatic steps, with the final insertion of molybdenum by Mo-insertase being poorly understood.

Purpose of the Study:

• To elucidate the mechanism of the final Moco maturation step catalyzed by the plant Mo-insertase Cnx1E.
• To investigate the structural basis for molybdate selectivity and insertion by Cnx1E.

Main Methods:

• Analysis of high-resolution X-ray crystallographic datasets of the plant Mo-insertase Cnx1E.
• Structural determination and analysis of molybdate-binding sites within the enzyme's active site.

Main Results:

• Two distinct molybdate-binding sites were identified within the active site of Cnx1E.
• The presence of molybdate in these sites correlates with a specific backbone conformation.

Conclusions:

• The identified molybdate-binding sites and associated conformational changes are crucial for the selectivity and efficiency of molybdate insertion by Mo-insertase.
• This study provides new insights into the molecular mechanisms of Moco biosynthesis.