Related Experiment Video
Updated: Nov 18, 2025

Visualization of DNA Compaction in Cyanobacteria by High-voltage Cryo-electron Tomography
Published on: July 17, 2018
Cryo-EM structures of engineered active bc1-cbb3 type CIII2CIV super-complexes and electronic communication between
Stefan Steimle1, Trevor van Eeuwen2, Yavuz Ozturk1,3
1Department of Biology, University of Pennsylvania, Philadelphia, PA, USA.
Abstract:
Respiratory electron transport complexes are organized as individual entities or combined as large supercomplexes (SC). Gram-negative bacteria deploy a mitochondrial-like cytochrome (cyt) bc1 (Complex III, CIII2), and may have specific cbb3-type cyt c oxidases (Complex IV, CIV) instead of the canonical aa3-type CIV. Electron transfer between these complexes is mediated by soluble (c2) and membrane-anchored (cy) cyts. Here, we report the structure of an engineered bc1-cbb3 type SC (CIII2CIV, 5.2 Å resolution) and three conformers of native CIII2 (3.3 Å resolution). The SC is active in vivo and in vitro, contains all catalytic subunits and cofactors, and two extra transmembrane helices attributed to cyt cy and the assembly factor CcoH. The cyt cy is integral to SC, its cyt domain is mobile and it conveys electrons to CIV differently than cyt c2. The successful production of a native-like functional SC and determination of its structure illustrate the characteristics of membrane-confined and membrane-external respiratory electron transport pathways in Gram-negative bacteria.
More Related Videos
09:25Do's and Don'ts of Cryo-electron Microscopy: A Primer on Sample Preparation and High Quality Data Collection for Macromolecular 3D Reconstruction
Published on: January 9, 2015
09:30Analyzing Dynamic Protein Complexes Assembled On and Released From Biolayer Interferometry Biosensor Using Mass Spectrometry and Electron Microscopy
Published on: August 6, 2018
Related Concept Videos
Cryo-electron Microscopy
The Supercomplexes in the Crista Membrane
Crystal Field Theory - Octahedral Complexes
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
Formation of Complex Ions
Electron Transport Chain: Complex III and IV
Ionic Crystal Structures
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...