Related Experiment Video

Updated: Mar 23, 2026

Examining Proteasome Assembly with Recombinant Archaeal Proteasomes and Nondenaturing PAGE: The Case for a Combined Approach
09:57

Examining Proteasome Assembly with Recombinant Archaeal Proteasomes and Nondenaturing PAGE: The Case for a Combined Approach

Published on: December 17, 2016

7.0K

Structural analysis of the dodecameric proteasome activator PafE in Mycobacterium tuberculosis

Lin Bai1, Kuan Hu2, Tong Wang1

  • 1Biosciences Department, Brookhaven National Laboratory, Upton, NY 11973;

Proceedings of the National Academy of Sciences of the United States of America
|March 23, 2016
PubMed

Insights

Mycobacterium tuberculosis proteasome accessory factor E (PafE) activates proteolysis without ATP. PafE forms unique dodecamers, revealing novel bacterial proteasome activation mechanisms beyond ATP-dependent enzymes.

Area of Science:

  • Microbiology
  • Structural Biology
  • Biochemistry

Background:

  • Mycobacterium tuberculosis (Mtb) relies on its proteasome system for virulence.
  • Proteasome accessory factor E (PafE) was previously identified as an activator of Mtb proteasome activity, independent of ATP.
  • PafE plays a role in Mtb's heat-shock response and overall virulence.

Purpose of the Study:

  • To elucidate the structural basis of PafE-mediated proteasome activation.
  • To investigate the unique features of PafE compared to eukaryotic proteasome activators.
  • To understand the role of PafE's carboxyl-terminus in proteasome binding and activity.

Main Methods:

  • Structural analysis of PafE subunits and dodecamer formation.
  • Biochemical assays to assess proteasomal activity upon PafE interaction.
  • Mutational analysis, including truncation of the PafE carboxyl-terminus.

Main Results:

  • PafE subunits assemble into dodecamers with 12-fold symmetry, featuring a unique glycine-rich motif.
  • These dodecamers resemble eukaryotic ATP-independent activators but possess distinct quaternary structures.
  • Truncation of PafE's carboxyl-terminus enhanced binding to the proteasome core particle and significantly boosted proteasomal activity.

Conclusions:

  • Bacterial proteasome activation is not solely dependent on ATP-consuming hexameric ATPases.
  • PafE represents a novel class of proteasome activators with unique structural and functional properties.
  • The carboxyl-terminus of PafE plays a regulatory role in its interaction with the Mtb proteasome core particle.
Keywords:
Mycobacterium tuberculosisX-ray crystallographycryo-EMproteasomestructural biology

More Related Videos

X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep105011:27

X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep1050

Published on: May 13, 2020

4.4K
Preparation of Mycobacterium Tuberculosis Culture Filtrate to Understand TB Pathogenesis07:32

Preparation of Mycobacterium Tuberculosis Culture Filtrate to Understand TB Pathogenesis

Published on: March 28, 2025

1.3K

Related Concept Videos

The Proteasome Structure01:17

The Proteasome Structure

The ubiquitin-proteasome pathway is a well-known mechanism utilized by eukaryotic cells to remove cytoplasmic proteins that are misfolded, damaged, or no longer needed. In this pathway, the protein that needs to be eliminated undergoes a process called ubiquitination, where a chain of ubiquitin molecules is attached to the 48th lysine residue of the target protein. This ubiquitin modification helps the proteasome distinguish between a target protein and a healthy protein.
The proteasome is an...
2.1K
Protein Complex Assembly02:41

Protein Complex Assembly

Proteins can form homomeric complexes with another unit of the same protein or heteromeric complexes with different types.  Most protein complexes self-assemble spontaneously via ordered pathways, while some proteins need assembly factors that guide their proper assembly. Despite the crowded intracellular environment, proteins usually interact with their correct partners and form functional complexes.
Many viruses self-assemble into a fully functional unit using the infected host cell to...
17.1K
Allosteric Proteins-ATCase01:19

Allosteric Proteins-ATCase

Binding sites linkages can regulate a protein's function.  For example, enzyme activity is often regulated through a feedback mechanism where the end product of the biochemical process serves as an inhibitor.
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to  N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis...
6.9K
Structure of Porins01:21

Structure of Porins

Mitochondria, chloroplasts, and gram-negative bacteria have transmembrane, beta-barrel proteins called porins to mediate the free diffusion of ions and metabolites across the membrane. Mitochondrial porin precursors contain conserved amino acid sequences called beta signals at their C-terminal. Beta signals have a  motif of PoXGXXHyXHy (Po-Polar, X-Any amino acid, G-Glycine, Hy-LargeHydrophobic), which are crucial for precursor recognition to initiate precursor assembly. Beta-barrel...
4.1K
Generation of Straight or Branched Actin Filaments01:14

Generation of Straight or Branched Actin Filaments

The straight or branched structure formation of actin filaments is controlled by nucleating proteins such as the formins and Arp2/3 complex. Formin-mediated assembly results in straight filaments, whereas Arp2/3 protein complex-mediated assembly results in branched actin filaments.
Arp2/3 Complex
Arp2/3 complex is a seven-subunit complex consisting of two proteins similar to actin- Arp2 and Arp3, and five other subunits that help keep Arp2 and Arp3 inactive. When required, the complex is...
4.0K