Relationship between local and global stabilities of proteins: site-directed mutants and chemically-modified derivatives of cytochrome c.


The methionine 80 sulfur-heme iron bond of rat cytochrome c, whose stability is decreased by mutating the phylogenetically invariant residue proline 30 to alanine and increased when tyrosine 67 is changed to phenylalanine, recovers its wild-type characteristics when both substitutions are performed on the same molecule. Titrations with urea, analyzed according to the heteropolymer theory [Alonso, D. O. V., & Dill, K. A. (1991) Biochemistry 30, 5974-5985], indicate that both single mutations increase the solvent exposure of hydrophobic groups in the unfolded state, while in the double mutant this conformational perturbation disappears. Similar increases in solvent exposure of hydrophobic groups are observed when the sulfur-iron bond of the wild-type protein is broken by alkylation of the methionine sulfur, by high pH, or by binding the heme iron with cyanide. The compensatory effects of the two single mutations do not extend to the overall stability of the protein. The added loss of conformational stability due to the single mutations amounts to 7.3 kcal/mol out of the 9 kcal/mol representing the overall free energy of stabilization of the native conformation of the wild-type protein. The folded conformation of the doubly mutated protein is only 2 kcal/mol less stable than that of the wild type. These results indicate that the double mutant protein is able to retain the essential folding pattern of cytochrome c and the thermodynamic stability of the methionine sulfur-heme iron bond, in spite of structural differences that weaken the overall stability of the molecule. Study holds ProTherm entries: 5320, 5321, 5322, 5323, 5324, 5325, 5326, 5327 Extra Details:

Submission Details

ID: fBKjDfUi

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:29 p.m.

Version: 1

Publication Details
Schejter A;Luntz TL;Koshy TI;Margoliash E,Biochemistry (1992) Relationship between local and global stabilities of proteins: site-directed mutants and chemically-modified derivatives of cytochrome c. PMID:1326327
Additional Information

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)

Relevant PDB Entries

Structure ID Release Date Resolution Structure Title
5DFS 2015-08-27T00:00:00+0000 1.15 Crystal structure of Spider Monkey Cytochrome C at 1.15 Angstrom
2B4Z 2005-09-27T00:00:00+0000 1.5 Crystal structure of cytochrome C from bovine heart at 1.5 A resolution.
2YBB 2011-03-02T00:00:00+0000 19.0 Fitted model for bovine mitochondrial supercomplex I1III2IV1 by single particle cryo-EM (EMD-1876)
3J2T 2012-12-23T00:00:00+0000 9.5 An improved model of the human apoptosome
5C0Z 2015-06-12T00:00:00+0000 1.12 The structure of oxidized rat cytochrome c at 1.13 angstroms resolution
5C9M 2015-06-28T00:00:00+0000 1.36 The structure of oxidized rat cytochrome c (T28A) at 1.362 angstroms resolution.
5DF5 2015-08-26T00:00:00+0000 1.3 The structure of oxidized rat cytochrome c (T28E) at 1.30 angstroms resolution.
5JUY 2016-05-10T00:00:00+0000 4.1 Active human apoptosome with procaspase-9
6FF5 2018-01-03T00:00:00+0000 1.74 X-ray structure of bovine heart cytochrome c at high ionic strength

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
95.2 Cytochrome c, somatic B4USV4 CYC_OTOGA
95.1 Cytochrome c, somatic P00021 CYC_COLLI
96.1 Cytochrome c, somatic P00020 CYC_ANAPL
93.3 Cytochrome c, somatic P81280 CYC_ALLMI
92.4 Cytochrome c, somatic Q52V10 CYC_SAISC
95.2 Cytochrome c, somatic P00012 CYC_MIRLE
99.0 Cytochrome c, somatic Q52V09 CYC_CEPBA
95.2 Cytochrome c, somatic P00013 CYC_MINSC
95.2 Cytochrome c, somatic P00014 CYC_MACGI
96.2 Cytochrome c, somatic P00011 CYC_CANLF
100.0 Cytochrome c, somatic P62898 CYC_RAT
98.1 Cytochrome c, somatic P00008 CYC_RABIT
100.0 Cytochrome c, somatic P62897 CYC_MOUSE
98.1 Cytochrome c, somatic P68098 CYC_LAMGU
98.1 Cytochrome c, somatic P68100 CYC_ESCRO
98.1 Cytochrome c, somatic P68099 CYC_CAMDR
96.2 Cytochrome c, somatic P00007 CYC_HIPAM
97.1 Cytochrome c P62896 CYC_SHEEP
97.1 Cytochrome c P62895 CYC_PIG
97.1 Cytochrome c P62894 CYC_BOVIN
99.0 Cytochrome c P68096 CYC_EQUBU
99.0 Cytochrome c P68097 CYC_EQUAS
100.0 Cytochrome c P00004 CYC_HORSE
91.3 Cytochrome c, somatic P21665 CYC_VARVA
91.4 Cytochrome c, somatic Q640U4 CYC1_XENTR
91.3 Cytochrome c, somatic Q6IQM2 CYC_DANRE
90.5 Cytochrome c, somatic Q7YR71 CYC_TRACR
90.4 Cytochrome c, somatic Q6DKE1 CYC2_XENLA
91.4 Cytochrome c, somatic P00024 CYC_LITCT
91.4 Cytochrome c, somatic P00022 CYC_CHESE
91.4 Cytochrome c, somatic Q5RFH4 CYC_PONAB
91.4 Cytochrome c, somatic P99998 CYC_PANTR
91.4 Cytochrome c, somatic P99999 CYC_HUMAN
91.4 Cytochrome c, somatic Q6WUX8 CYC_GORGO
90.5 Cytochrome c, somatic P00003 CYC_ATESP
92.4 Cytochrome c, somatic P00019 CYC_STRCA
92.4 Cytochrome c, somatic Q52V08 CYC_MACSY
92.4 Cytochrome c, somatic P00002 CYC_MACMU
92.4 Cytochrome c, somatic P00018 CYC_DRONO
92.4 Cytochrome c, somatic P67882 CYC_MELGA
92.4 Cytochrome c, somatic P67881 CYC_CHICK
92.4 Cytochrome c, somatic P00017 CYC_APTPA