A study of roles of evolutionarily invariant proline 30 and glycine 34 of cytochrome c.
Abstract: The previous studies (Juillerat, M. A., and Taniuchi, H. (1986) J. Biol. Chem. 261, 2697-2711), using a three-fragment complex (1-25)H X (28-38) X (39-104) of horse cytochrome c, have shown that invariant leucine 32 and partially invariant leucine 35, both buried in the interior, exhibit a striking difference in perturbation of binding fragment (28-38) by substitution with isoleucine. Then the idea has been proposed that the energy states of leucine 32, the Met-80-S-heme-Fe bond and other distant residues such as tryptophan 59 would be coupled to generate extra force while leucine 35 would be less important for such coupling if it were involved. In the present studies we synthesized three (28-38) analogs substituting invariant proline 30 with glycine or invariant glycine 34 with alanine or serine. Thermodynamic and kinetic studies and UV CD and biological activity measurements were carried out on binding of the analogs to complex (1-25)H X (39-104). The results with the ferric form show that perturbations of delta G, delta H, and delta S associated with formation of the intermediate complex and with the ensuing process by the Gly34----Ala or Ser substitution result in weakening the Met-80-S-heme-Fe bond formed in the latter process; in contrast, perturbation by the Pro30----Gly substitution is small. However, the biological activity is more perturbed by the Pro30----Gly substitution than by the Gly34----Ala or Ser; and in the Gly34----Ala or Ser substitution the complex appears to be more readily activated for both formation and disruption of the Met-80-S-heme-Fe bond at 20 degrees C and below than without substitution. In all cases reduction of the heme strengthens the binding of fragment (28-38). However, striking are the increases in perturbation (less negative) of both delta H and delta S for binding of fragment (28-38) to form the ground state on reduction of the heme in the Pro30----Gly, Gly34----Ala or Ser (the present studies), and Leu32----norvaline (the previous studies) substitutions. It is known that fluctuation of the atomic positions of most residues of tuna ferrocytochrome c including Pro30, Leu32, and Gly34 increases on oxidation of the heme and that these three residues are among those showing the least fluctuating atomic positions (Takano, T., and Dickerson, R.E. (1982) in Electron Transport and Oxygen Utilization (Ho, C., ed) pp. 17-26, Elsevier/North-Holland Biomedical Press, New York).(ABSTRACT TRUNCATED AT 400 WORDS)
Publication Date: 1986-08-25 PubMed ID: 3015948
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- Journal Article
Summary
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This research investigates the roles of proline 30 and glycine 34, which are evolutionarily invariant, in the protein cytochrome c, a component involved in cellular energy production. The study experiments with swapping these amino acids and assessing the impact on binding and activation, providing insight into the protein’s functionality and the influence of these specific amino acids.
Study Context and Objectives
- This was a follow-up of earlier research which had examined the role of leucine 32 and leucine 35 in cytochrome c and demonstrated a significant difference in binding fragment changes upon their substitution with isoleucine. Proline 30 and glycine 34 were selected for this study as they are evolutionarily invariant — across different species, these parts are conserved without variation.
- The objective of the study was to assess the importance of proline 30 and glycine 34 for the binding and function of cytochrome c.
Study Method
- The researchers synthesized three variations of a segment of cytochrome c, each replacing either proline 30 with glycine, or glycine 34 with alanine or serine.
- Through thermodynamic and kinetic studies, UV CD (circular dichroism) and biological activity measurements, they assessed the impact of these substitutions on the binding and functional capacity of the corresponding protein complexes.
Study Findings
- Findings indicated that substitutions of glycine 34 with either alanine or serine resulted in significant functional disturbances, particularly affecting the Met-80-S-heme-Fe bond, an important interaction in the cytochrome c protein complex.
- In contrast, the substitution of proline 30 with glycine caused smaller perturbations in the thermodynamic and kinetic properties of the protein.
- However, the proline 30 substitution was observed to cause greater disruptions in the protein’s biological activity compared to the glycine 34 substitution.
- All experiments showed that reduction of the heme (the central component of hemoglobin) strengthened the binding of the substituted segments, and especially produced notable changes for proline 30 or glycine 34 substitutions.
Conclusion and Implications
- The research has provided insight into the roles of proline 30 and glycine 34 in cytochrome c functionality.
- Considering the functional disturbances caused by these substitutions, these residues (proline 30 and glycine 34) are likely important for the normal functioning of the protein, and by extension, effective cellular energy production.
- The results also indicate a potential regulatory role for heme reduction in cytochrome c function.
Cite This Article
APA
Poerio E, Parr GR, Taniuchi H.
(1986).
A study of roles of evolutionarily invariant proline 30 and glycine 34 of cytochrome c.
J Biol Chem, 261(24), 10976-10989.
Publication
Researcher Affiliations
MeSH Terms
- Amino Acid Sequence
- Animals
- Circular Dichroism
- Cytochrome c Group / metabolism
- Glycine / analysis
- Horses
- Kinetics
- Mathematics
- Molecular Conformation
- Myocardium / enzymology
- Proline / analysis
- Spectrophotometry, Ultraviolet
- Thermodynamics
Citations
This article has been cited 3 times.- Zaidi S, Hassan MI, Islam A, Ahmad F. The role of key residues in structure, function, and stability of cytochrome-c.. Cell Mol Life Sci 2014 Jan;71(2):229-55.
- Taniuchi H, Shi Y, San Miguel GI, Ferretti JA, Mack JW, Fisher A, Shah M, Schechter AN, Shiloach J. A study of the influence of the hydrophobic core residues of yeast iso-2-cytochrome c on phosphate binding: a probe of the hydrophobic core-surface charge interactions.. J Protein Chem 2001 Apr;20(3):203-15.
- Koshy TI, Luntz TL, Schejter A, Margoliash E. Changing the invariant proline-30 of rat and Drosophila melanogaster cytochromes c to alanine or valine destabilizes the heme crevice more than the overall conformation.. Proc Natl Acad Sci U S A 1990 Nov;87(22):8697-701.
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