A research study short article in Nature has shed light on the structure and function of breathing supercomplexes in cellular respiration, especially in a single-cell eukaryote, Tetrahymena thermophila. The research study combined various methods to demonstrate that all four breathing complexes in this organism associate together to form a huge supercomplex including 150 proteins and 311 lipids, which significantly affects the shape of the mitochondrial membrane. Credit: luminous-lab. com.
A new research study has actually exposed how respiratory supercomplexes, including four associated breathing complexes, shape the mitochondrial membrane in the single-cell eukaryote, Tetrahymena thermophila. The research study revealed these supercomplexes have both a structural and enzymatic function, enhancing ATP synthesis and supporting energy conversion. The discovery of a split and extended subunit, COX3, highlights an evolutionary system advantageous for inter-complex contacts.
Eukaryotes generate the energy for survival through cellular respiration in mitochondria by a procedure understood as the oxidative phosphorylation. In this procedure, nutrients and oxygen are converted into a chemical type of energy– the ATP. This is accomplished with a proton gradient developed by the electron transport chain inside mitochondria. The gradient is driven by a series of 4 respiratory complexes in the inner mitochondrial membrane.
A study released in the journal Nature integrated single-particle, tomography, molecular simulations and biophysics to clarify bioenergetic macro-assemblies and how they form mitochondrial membranes. It identified that In Tetrahymena thermophila– a free-living single cell eukaryote discovered in ponds and lakes, all four breathing complexes are associated together. They form a huge 5.8 megadalton supercomplex of 150 proteins with at least 300 transmembrane helices and 311 lipids. Owing to subunit acquisition and extension, Complex I binds a dimer of Complex III that is slanted by 37 degrees. Complex I also connects with Complex IV dimer, generating a space that acts as a binding site for Complex II. The study demonstrates that this assembly is essential to the shaping of the bioenergetic membrane.
The advancement of protein subunits of breathing complexes has led to the I– II– III2– IV2 assembly that adds to the shaping of the bioenergetic membrane, therefore enabling its practical specialization.
One of the most interesting findings is that a subunit of Complex IV called COX3 is split in 2. The fragmentation takes place on the genetic level, and after that each fragment is extended contributing to a few of the user interfaces between complexes. The gain of function for inter-complex contacts represents an evolutionary system, revealing how neutral molecular intricacy can become beneficial.
The findings highlight how the evolution of protein subunits of breathing complexes has actually resulted in the suercomplex assembly, which actively adds to mitochondrial membrane curvature induction, which is needed for proper mitochondrial function. In this manner, the supercomplex shapes the macroscopic architecture of mitochondria, ultimately optimizing ATP synthesis. Breathing supercomplexes have not only an enzymatic but likewise a structural function of shaping the membrane, and both together support energy conversion and offer fuel for life.
For more on this research study, see Scientists Identify Complete Respiratory Supercomplex.
Referral: “Structural basis of mitochondrial membrane flexing by the I– II– III2– IV2 supercomplex” by Alexander Mühleip, Rasmus Kock Flygaard, Rozbeh Baradaran, Outi Haapanen, Thomas Gruhl, Victor Tobiasson, Amandine Maréchal, Vivek Sharma and Alexey Amunts, 22 March 2023, Nature.DOI: 10.1038/ s41586-023-05817-y.
The study integrated various strategies to show that all 4 respiratory complexes in this organism associate together to form a massive supercomplex consisting of 150 proteins and 311 lipids, which substantially influences the shape of the mitochondrial membrane. A new research study has actually revealed how breathing supercomplexes, consisting of four associated respiratory complexes, form the mitochondrial membrane in the single-cell eukaryote, Tetrahymena thermophila. Owing to subunit acquisition and extension, Complex I binds a dimer of Complex III that is slanted by 37 degrees. Complex I likewise associates with Complex IV dimer, creating a space that serves as a binding website for Complex II.
