Molecular evolution of biotin-dependent carboxylases

Area of Science:

• Biochemistry
• Molecular Biology
• Enzymology

Background:

• Biotin-dependent carboxylases are crucial enzymes utilizing three functional units: biotin carboxylase, biotin-carboxyl-carrier protein, and carboxyl transferase.
• These enzymes, excluding specific exceptions, rely on these units for their catalytic activity.
• Known homologies exist between biotin carboxylase and carbamoyl-phosphate synthetase, and between biotin-carboxyl-carrier protein and lipoic-acid-binding domains.

Purpose of the Study:

• To investigate the amino-acid sequences of the three functional units in biotin-dependent carboxylases.
• To gain insights into the structure, function, and molecular evolution of these enzymes.
• To propose a model for the evolutionary history of biotin-dependent carboxylases.

Main Methods:

• Computer-assisted sequence comparison of functional units.
• Molecular phylogenetic analysis.
• Secondary structure prediction based on sequence similarity.

Main Results:

• Identified evolutionary relationships between functional units and their homologues.
• Proposed a model for the evolutionary history of biotin-dependent carboxylases, explaining diverse domain/subunit structures.
• Discovered a repeated structure within the biotin-carboxyl-carrier protein.

Conclusions:

• The study provides a comprehensive understanding of the molecular evolution of biotin-dependent carboxylases.
• The proposed evolutionary model explains the diversification of enzyme structures.
• Structural insights into biotin-carboxyl-carrier protein were gained through sequence analysis.