Expanding the Versatility of Microbial Transglutaminase Using α-Effect Nucleophiles as Noncanonical Substrates

Area of Science:

• Biochemistry
• Biotechnology
• Enzymology

Background:

• Microbial transglutaminase (mTG) is known for attaching alkyl amines to glutamine residues in peptides and proteins.
• This enzymatic activity is crucial for various biotechnological applications.

Purpose of the Study:

• To expand the substrate scope of mTG beyond traditional amines.
• To explore new bioconjugation strategies using mTG with novel substrates.
• To develop site-specific bioconjugates with tunable properties.

Main Methods:

• Investigated mTG's reactivity with hydrazines, hydrazides, and alkoxyamines.
• Demonstrated the installation of hydrazide handles onto glutamine residues.
• Utilized hydrazide handles for coupling with carbonyl compounds, including ortho-carbonylphenylboronic acids.

Main Results:

• mTG successfully formed isopeptide bonds with hydrazines, hydrazides, and alkoxyamines.
• New isopeptide bonds exhibited varied susceptibility to hydrolysis and exchange.
• Site-specific bioconjugates were formed with tunable hydrolytic stability.

Conclusions:

• The substrate repertoire of mTG was significantly broadened.
• New bioconjugation approaches using mTG were established.
• This enhances the enzyme's versatility for novel biotechnological applications.