Enzymes interacting with sugars and proteins within a cell.

Unlocking Cellular Secrets: How Sugar and Protein Interactions Could Revolutionize Medicine

Lena Kashyap in Science & Nature June 2025 • 4 min read.

"Decoding the Specificity of N-acetyltransferases for New Therapeutic Strategies"

In the realm of molecular biology, N-terminal acetylation stands out as a pivotal post-translational modification. Affecting approximately 85% of eukaryotic proteins, this process influences various cellular functions, from DNA binding and protein-protein interactions to overall protein stability. Understanding N-terminal acetylation is not just an academic pursuit; it has profound implications for both normal cell biology and the understanding of pathological conditions.

Central to this process are N-terminal acetyltransferases (NATs), enzymes that catalyze the transfer of an acetyl moiety from acetyl coenzyme A (Acetyl-CoA) to a primary amine group on acceptor substrates. These substrates range from small molecules like aminoglycosides to large macromolecules, including diverse proteins. NATs are members of the GCN-5 related N-acetyltransferases family (GNAT), a vast group with over 100,000 members across all life kingdoms. Despite their abundance, sequence conservation within the GNAT superfamily is limited, reflecting their diverse substrate-binding and modifying capabilities.

Eukaryotic NATs, such as NatA-F, are essential in protein N-terminal acetylation, differing in subunit composition, substrate preferences, and resulting phenotypes. Although N-acetylated proteins are abundant in eukaryotes, only a few bacterial proteins have been found to undergo similar modifications. Recent research has focused on NATs like RimI, RimJ, and RimL from Salmonella enterica and YhY from Escherichia coli, believed to be homologs of eukaryotic NATs. A recent study sheds light on the unexpected capabilities of two NATs, GlmA and RmNag, derived from Clostridium acetobutylicum and Rhizomucor miehei, respectively. These enzymes, traditionally defined as glucosamine NATs, can also acetylate the free amino group on the first glycine residue of peptides. The research also includes human NAT Naa10p to widen the comparison and selectivity ranges.

What Makes These Enzymes Unique? Exploring Substrate Specificity

Enzymes interacting with sugars and proteins within a cell.

The study explores the substrate selectivity of three N-acetyltransferases – GlmA from Clostridium acetobutylicum, RmNag from Rhizomucor miehei, and Naa10p, a human recombinant N-acetyltransferase – against a range of hexosamines and synthetic peptides. GlmA and RmNag, previously identified as glucosamine N-acetyltransferases, surprisingly showed the capacity to acetylate the free amino group on the first glycine residue of peptides, albeit with varying catalytic efficiency. In contrast, Naa10p exhibited a preference for primary amine groups in peptides over glucosamine.

Researchers conducted several experiments to understand the enzymes' preferences:

Hexosamine Specificity: The enzymes were tested against glucosamine (GlcN), galactosamine (GalN), and mannosamine (ManN). All three NATs could acetylate GlcN, although Naa10p showed lower efficiency. RmNag could also partially acetylate GalN.
Peptide Acetylation: GlmA and RmNag could acetylate peptides starting with glycine, indicating broader substrate specificity than initially thought.
Residue Preferences: Further tests revealed that both enzymes disliked negatively charged residues at the +2 or +3 positions following the N-terminal glycine. RmNag showed more flexibility and efficiency in peptide acetylation compared to GlmA.
Comparison with GlcN-Linked Peptides: GlmA preferred GlcN over peptides, while RmNag showed almost equal activity towards both, suggesting diverse roles in cellular metabolism. Naa10p preferred peptides with acidic N-termini over GlcN.

These findings indicate that the varied preferences of GlmA, RmNag, and Naa10p likely stem from their divergent evolution. Understanding the acceptor specificity of these NATs is crucial for their application in acetylating hexosamines or specific peptides. For instance, GlmA's preference for GlcN makes it ideal for producing GlcNAcylated peptides, while Naa10p's affinity for acidic N-termini peptides highlights its role in protein modification.

Future Implications and Applications

In conclusion, this research provides a comprehensive comparison of three distinct NATs, revealing their unique substrate preferences. GlmA is best suited for modifying glucosamine, while Naa10p excels in peptide N-terminal acetylation. RmNag, with its flexible substrate selectivity, may play diverse roles in cellular metabolism. By understanding these enzymes' specificities, researchers can better apply them in biotechnological applications and develop targeted therapies.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1016/j.carres.2018.11.011, Alternate LINK

Title: N-Acetyltransferases From Three Different Organisms Displaying Distinct Selectivity Toward Hexosamines And N-Terminal Amine Of Peptides

Subject: Organic Chemistry

Journal: Carbohydrate Research

Publisher: Elsevier BV

Authors: Peiru Zhang, Pei Liu, Yangyang Xu, Yulu Liang, Peng George Wang, Jiansong Cheng

Published: 2019-01-01

Everything You Need To Know

What are N-terminal acetyltransferases (NATs), and what role do they play in cells?

N-terminal acetyltransferases, or NATs, are enzymes that catalyze the transfer of an acetyl group from acetyl coenzyme A (Acetyl-CoA) to substrates, including proteins and small molecules. They belong to the GCN-5 related N-acetyltransferases family (GNAT). These enzymes play a crucial role in protein N-terminal acetylation, a process affecting about 85% of eukaryotic proteins and influencing various cellular functions such as DNA binding, protein-protein interactions, and protein stability. Further research into NATs could reveal new insights into biotechnological applications and targeted therapies.

Which N-acetyltransferases were examined in this study, and what surprising capabilities were discovered?

The study examined three N-acetyltransferases: GlmA from Clostridium acetobutylicum, RmNag from Rhizomucor miehei, and Naa10p, a human recombinant N-acetyltransferase. GlmA and RmNag, traditionally known as glucosamine N-acetyltransferases, surprisingly acetylated the free amino group on the first glycine residue of peptides. Naa10p, on the other hand, preferred primary amine groups in peptides over glucosamine. This variance highlights the different roles each enzyme plays and illuminates potential applications for targeted therapies.

How do the substrate preferences of GlmA, RmNag, and Naa10p differ, and what are the implications of these differences?

GlmA exhibits a preference for glucosamine (GlcN) over peptides, making it ideal for producing GlcNAcylated peptides. Naa10p shows a strong affinity for peptides with acidic N-termini, suggesting its significance in protein modification. RmNag displays more flexible substrate selectivity, indicating its involvement in diverse cellular metabolic processes. These specificities are crucial for applying these enzymes in biotechnological applications and drug development.

What is N-terminal acetylation, and why is it important in cellular biology?

N-terminal acetylation is a post-translational modification affecting approximately 85% of eukaryotic proteins. This process involves the addition of an acetyl group to the N-terminus of a protein, influencing critical cellular functions such as DNA binding, protein-protein interactions, and overall protein stability. The specificity of enzymes like N-terminal acetyltransferases (NATs) in this process has implications for understanding both normal cell biology and pathological conditions, suggesting avenues for therapeutic interventions.

Based on this research, what are the potential future applications of understanding the substrate specificity of different N-acetyltransferases (NATs)?

The research findings suggest that different N-acetyltransferases (NATs) have unique substrate preferences, stemming from their evolutionary divergence. For example, GlmA is well-suited for modifying glucosamine, while Naa10p excels in peptide N-terminal acetylation. RmNag, with its flexible substrate selectivity, may play varied roles in cellular metabolism. Understanding these enzymes' specificities allows researchers to better apply them in biotechnological applications and develop targeted therapies, potentially revolutionizing personalized medicine by manipulating sugar and protein interactions.