Yeast iso-1-cytochrome c. A 2.8 A resolution three-dimensional structure determination

Area of Science:

• Biochemistry
• Structural Biology
• Molecular Genetics

Background:

• Cytochromes c are essential electron transport proteins found in eukaryotes.
• Understanding their structure is key to elucidating function and evolutionary relationships.

Purpose of the Study:

• To determine the high-resolution structure of yeast iso-1-cytochrome c.
• To identify unique structural features compared to other eukaryotic cytochromes c.
• To correlate structural findings with observed functional alterations in mutant proteins.

Main Methods:

• Molecular replacement method.
• Predictive modeling procedures.
• Solvent accessibility studies.
• Packing analyses.
• Translational coefficient searches.

Main Results:

• Elucidation of the 2.8 A resolution structure of yeast iso-1-cytochrome c.
• Identification of unique conformations in the N-terminus, a surface beta-loop (residues 19-26), and the C-terminal heme pocket region.
• Buried sulfhydryl group of Cys102 in the monomer, requiring conformational change for dimerization.
• Surface-exposed trimethylated Lys72 near the heme group.
• Classification of heme pocket residues into three spatial conservation classes.

Conclusions:

• The determined structure provides insights into the unique folding of yeast iso-1-cytochrome c.
• Structural variations explain altered functional properties in mutant yeast iso-1-cytochrome c proteins.
• Comparative analysis of heme pocket structures advances understanding of cytochrome c evolution and function.