GMP Synthetase: Allostery, Structure, and Function.

Area of Science:

• Biochemistry
• Enzymology
• Structural Biology

Background:

• Glutamine amidotransferases (GATs) catalyze glutamine hydrolysis and ammonia transfer.
• These enzymes possess two distinct catalytic sites linked by an ammonia channel.
• GMP synthetase (GMPS) is a GAT essential for the de novo guanosine monophosphate synthesis pathway.

Purpose of the Study:

• To provide a comprehensive assessment of the molecular basis of catalysis in GMP synthetase (GMPS).
• To review the current understanding of GMPS biochemical function, particularly its acceptor domain catalysis and inter-domain communication.
• To highlight advancements in understanding GMPS structure-function relationships, especially following the determination of a glutamine-bound mutant structure.

Main Methods:

• Review of existing literature and crystal structures of GATs and GMPS.
• Analysis of structural data to elucidate ammonia channeling and conformational changes.
• Integration of biochemical and structural information to understand enzyme catalysis.

Main Results:

• While ammonia channels are evident in most GAT structures, GMPS catalysis understanding lagged until specific mutant structures were resolved.
• Structural insights reveal conformational changes critical for coordinating dual catalytic activities.
• The review synthesizes current knowledge on GMPS's molecular mechanisms.

Conclusions:

• Understanding GMPS catalysis has significantly advanced through structural biology, particularly studies of mutants.
• The enzyme's dual catalytic sites and ammonia channeling are key to its function.
• This review consolidates current knowledge, offering insights into this important enzyme's biochemical function.