Related Experiment Video

Updated: Feb 1, 2026

RhoC GTPase Activation Assay
09:58

RhoC GTPase Activation Assay

Published on: August 22, 2010

13.0K

Hexameric assembly of the AAA+ protein McrB is necessary for GTPase activity

Neha Nirwan1, Pratima Singh1, Gyana Gourab Mishra1

  • 1Division of Biology, Indian Institute of Science Education and Research, Pune 411008, India.

Nucleic Acids Research
|December 7, 2018
PubMed

Insights

The Escherichia coli McrBC enzyme, a restriction enzyme, forms a hexameric structure. This complex assembly of McrB hexamers and McrC subunits is crucial for its DNA cleavage activity.

Area of Science:

  • Molecular biology
  • Enzymology
  • Bacterial genetics

Background:

  • McrBC is a modification-dependent restriction enzyme in Escherichia coli K12.
  • It uniquely utilizes an AAA+ domain for GTP hydrolysis-dependent DNA cleavage.
  • Previous studies suggested McrB and McrC subunits oligomerize.

Purpose of the Study:

  • To elucidate the solution structure and oligomeric state of McrB and McrBC.
  • To understand the mechanism of McrBC activation and its relation to GTP hydrolysis.
  • To investigate the role of specific domains and residues in McrBC function.

Main Methods:

  • Size exclusion chromatography coupled multi-angle light scattering (SEC-MALS).
  • Electron cryomicroscopy (cryo-EM).
  • Small-angle X-ray scattering (SAXS).
  • Mutational studies of McrB.

Main Results:

  • McrB exists as a hexamer in solution.
  • McrBC is proposed to be a complex of two McrB hexamers bridged by two McrC subunits.
  • Nucleotide-dependent oligomerization of McrB precedes GTP hydrolysis.
  • The catalytic Walker B aspartate in McrB is essential for oligomerization, unlike in other AAA+ proteins.

Conclusions:

  • The hexameric structure of McrB and the complete McrBC complex assembly are integral to its enzymatic activity.
  • Oligomerization is a prerequisite for GTP hydrolysis in McrBC function.
  • The catalytic domain's role in oligomerization is unique to McrBC among AAA+ proteins.

More Related Videos

Detection of Small GTPase Prenylation and GTP Binding Using Membrane Fractionation and GTPase-linked Immunosorbent Assay13:51

Detection of Small GTPase Prenylation and GTP Binding Using Membrane Fractionation and GTPase-linked Immunosorbent Assay

Published on: November 11, 2018

10.4K
Comparing the Affinity of GTPase-binding Proteins using Competition Assays10:37

Comparing the Affinity of GTPase-binding Proteins using Competition Assays

Published on: October 8, 2015

9.6K

Related Concept Videos

Coat Assembly and GTPases01:33

Coat Assembly and GTPases

Vesicles incorporate different coat protein subunits in different cell locations, which changes the properties of the coat, such as the shape and geometry of the transport vesicles. Thus, vesicle coat proteins also play a significant role in cargo selection.
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
4.4K
GTPases and their Regulation02:14

GTPases and their Regulation

Guanine nucleotide-binding proteins (G-proteins), also known as GTPases, are a superfamily of proteins that regulate many cellular processes, such as cell signaling, vesicular transport, and the regulation of cell shape and motility. Mutation or dysfunction of these proteins can lead to disease. There are around 40,000 known G-proteins that can broadly be classified into two groups ‒  small G-proteins consisting of a single domain and large multi-domain G-proteins.
Large G-proteins,...
9.8K
GTPases and their Regulation02:14

GTPases and their Regulation

3.0K
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...
16.8K
Protein Complex Assembly02:41

Protein Complex Assembly

2.6K
Small GTPases - Ras and Rho01:24

Small GTPases - Ras and Rho

Ras and Rho are small monomeric GTPases that act downstream of receptor tyrosine kinase (RTK) and regulate various cellular processes. These GTPases switch between active and inactive states by binding to guanine nucleotides.
Three regulatory proteins control their activity:
5.4K