NMR Structure and Dynamics Studies of Yeast Respiratory Supercomplex Factor 2.

Area of Science:

• Mitochondrial biology
• Protein structure and function
• Biochemistry

Background:

• Saccharomyces cerevisiae respiratory supercomplex factor 2 (Rcf2) is vital for forming respiratory supercomplexes.
• Rcf2 is located in the mitochondrial inner membrane.
• Previous work showed Rcf2 forms dimers in micelles.

Purpose of the Study:

• Determine the solution NMR structure of the Rcf2 dimer.
• Investigate the role of the C-terminal transmembrane helix in dimer formation.
• Explore Rcf2 structural dynamics in a lipid environment.

Main Methods:

• Solution Nuclear Magnetic Resonance (NMR) spectroscopy to determine Rcf2 dimer structure.
• Analysis of Nuclear Overhauser Effect (NOE) contacts to identify inter-monomer interactions.
• NMR chemical shift mapping and molecular dynamics simulations to study lipid interactions.

Main Results:

• The solution NMR structure of the Rcf2 dimer was resolved.
• Each monomer contains soluble and transmembrane α helices, with a charged C-terminal TM helix.
• Inter-monomer salt bridges and hydrogen bonds stabilize the dimer interface.
• Lipid titrations and simulations suggest structural changes upon membrane embedding.

Conclusions:

• The charged C-terminal TM helix is essential for Rcf2 dimer formation and stabilization.
• Structural insights into Rcf2 provide a basis for understanding respiratory supercomplex assembly.
• Rcf2 exhibits dynamic structural adaptations to its native lipid environment.