Polypeptide tags, ubiquitous modifiers for plant protein regulation

Area of Science:

• Plant Molecular Biology
• Cellular Regulation
• Post-Translational Modification

Background:

• Plants, animals, and fungi employ polypeptide tags to modify protein function, structure, location, and turnover.
• Known plant polypeptide tags include ubiquitin, SUMO, RUB, and APG12, with potential for others.
• These tags are typically attached post-translationally via conjugase pathways, forming isopeptide bonds with target proteins.

Purpose of the Study:

• To review the evidence for polypeptide tags in plants.
• To highlight the diverse roles and mechanisms of these protein modifiers.
• To emphasize the significance of polypeptide tagging in plant cell regulation.

Main Methods:

• Literature review of existing evidence on polypeptide tagging in plants.
• Analysis of known polypeptide tags (ubiquitin, SUMO, RUB, APG12) and their modification pathways.
• Comparison of the roles and target specificity of different polypeptide tags.

Main Results:

• Ubiquitin is the most influential tag, primarily signaling protein degradation via the 26S proteasome.
• SUMO, RUB, and APG12 target fewer proteins but have specialized roles in nuclear pore function, cell-cycle regulation, and vacuole trafficking.
• Tag removal is often mediated by specific proteases, though co-translational fusion also occurs.

Conclusions:

• Polypeptide tags are integral to plant cellular regulation.
• The diversity and widespread occurrence of these tags underscore their prominent role in various biological processes.
• Understanding these tagging systems is key to deciphering complex plant cell functions.