The role of histidines 26 and 33 in the structural stabilization of cytochrome c.


Comparative studies of the importance of the two histidines of rat cytochrome c that are not ligands of the heme iron, for the stability of the protein, were carried out by site-directed mutagenesis. Histidine 26 was substituted by valine and the resulting effects on the stability of the Met-80-sulfur to heme iron bond to changes in pH and temperature, and of the global stability of the protein to unfolding in urea solutions, were measured. It is suggested that the loss of the hydrogen bond between the His-26 imidazole and the backbone amide of Asn-31 caused the observed decreases in local stability; and that, in addition, the elimination of the hydrogen bond between this imidazole and the carbonyl of Pro-44 resulted in an increase of the mobility of the lower loop (residues 41-47) on the right side of the protein and of its distance from the middle loop (residues 26-31), probably leading to greater hydration of the interior right side of the molecule. These changes resulted in a decrease in the global stability of the protein. Further mutation of Asn-52 to Ile led to a total recovery of the wild-type stability of the sulfur-iron bond, and a partial restoration of the global stability of the protein. Substitution of Phe for His-33 did not alter the sulfur-iron bond but caused a pronounced increase in the global stability of the protein. It is suggested that this effect results from hydrophobic interaction of the Phe-33 side chain with the lower loop on the right side of the protein. Such an interaction also explains the observation that the same mutation reversed the loss of global stability caused by substitution of Val to His-26, but did not restore the strength of the sulfur-iron bond that this mutation had brought about. Study holds ProTherm entries: 9341, 9342, 9343, 9344, 9345, 9346, 9347, 9348, 9349, 9350, 9351, 9352, 9353, 9354, 9355, 9356, 9357, 9358, 9359, 9360 Extra Details:

Submission Details

ID: mBnNukY6

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:37 p.m.

Version: 1

Publication Details
Qin W;Sanishvili R;Plotkin B;Schejter A;Margoliash E,Biochim. Biophys. Acta (1995) The role of histidines 26 and 33 in the structural stabilization of cytochrome c. PMID:7548170
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