Database accession: MF7000593
Name: S100A1 (apo form) with disulfide between CYS85 residue and b-mercaptoethanol
PDB ID: 2jpt
Experimental method: NMR
Assembly: Homodimer
Source organism: Bos taurus
Primary publication of the structure:
Zhukov I, Ejchart A, Bierzyński A
Structural and motional changes induced in apo-S100A1 protein by the disulfide formation between its Cys 85 residue and beta-mercaptoethanol.
(2008) Biochemistry 47: 640-50
PMID: 18088104
Abstract:
Recently, we have shown (Goch, G., Vdovenko, S., Kozłowska, H., and Bierzyński, A. (2005) FEBS J. 272, 2557-2565) that the chemical modification of Cys 85 residue of S100A1 protein by disulfide bond formation with small thiols such as glutathione, cysteine, or beta-mercaptoethanol (betaME) leads to a dramatic increase of the protein affinity for calcium. Therefore, the biological function of S100A1 as a calcium signal transmitter is probably regulated by the redox potential within the cell. Systematic, structural studies of various mixed disulfides of S100A1 in the apo and holo states are necessary to elucidate the mechanism of this phenomenon. Using NMR methods we have determined the structure of apo-S100A1-betaME and, on the basis of 15N nuclear magnetic relaxation data, we have characterized the structural dynamics of both: modified and unmodified molecules of apo-S100A1. The following effects of betaME modification have been observed: (1) Helices IV and IV' of two protein subunits are elongated by five residues (85-89). (2) Conformation of the calcium binding N-terminal loops is dramatically changed, and structural flexibility of the N-loops as well as C-loops markedly increases. (3) The angle between helices I and IV increases by approximately 20 degrees and between helices IV and IV' decreases by approximately 35 degrees . All these observations lead to the conclusion that betaME modification of apo-S100A1 makes its structure more similar to that of holo-S100A1, so that it becomes much better adjusted for calcium coordination.
Annotations from the GeneOntology database. Only terms that fit at least two of the interacting proteins are shown. Molecular function:
calcium ion binding calcium ion binding
calcium-dependent protein binding calcium-dependent protein binding
S100 protein binding S100 protein binding
Biological process:
regulation of heart contraction regulation of heart contraction
Cellular component:
cytoplasm cytoplasm
mitochondrion mitochondrion
sarcoplasmic reticulum sarcoplasmic reticulum
Structural annotations of the participating protein chains.Entry contents: 2 distinct polypeptide molecules
Chains: A, B
Notes: All chains according to the most probable oligomerization state stored in PDBe were considered.
Number of unique protein segments: 1
Name: Protein S100-A1
Source organism: Bos taurus
Length: 94 residues
Sequence:Sequence according to the corresponding UniProt protein segmentMGSELETAMETLINVFHAHSGKEGDKYKLSKKELKELLQTELSGFLDAQKDADAVDKVMKELDENGDGEVDFQEYVVLVAALTVACNNFFWENS
UniProtKB AC: P02639 (positions: 2-94)
Coverage: 98%
Name: Protein S100-A1
Source organism: Bos taurus
Length: 94 residues
Sequence:Sequence according to the corresponding UniProt protein segmentMGSELETAMETLINVFHAHSGKEGDKYKLSKKELKELLQTELSGFLDAQKDADAVDKVMKELDENGDGEVDFQEYVVLVAALTVACNNFFWENS
UniProtKB AC: P02639 (positions: 2-94)
Coverage: 98%
Evidence demonstrating that the participating proteins are unstructured prior to the interaction and their folding is coupled to binding. Representative domain in related structures: S-100/ICaBP type EF hand dimer
Evidence level: Direct evidence
Evidence coverage: The full structure participates in mutual synergistic folding.
Complex Evidence:
GuHCl-induced denaturation of the S100B protein dimer showed that it follows a two-state unfolding/refolding process (PMID:11888280). Other S100 proteins also showed two-state unfolding, no folded monomers were observed (PMID:18346834, PMID:18706914). The dimer has a globular and compact structure with the four helices in each subunit aligning to form a unicornate-type four-helix bundle (PMID:11790100). The hydrophobic core extends through the dimer interface.
Chain A:
N/A
Chain B:
N/A
Surface and contacts features:
Structures from the PDB that contain the same number of proteins, and the proteins from the two structures show a sufficient degree of pairwise similarity, i.e. they belong to the same UniRef90 cluster (the full proteins exhibit at least 90% sequence identity) and convey roughly the same region to their respective interactions (the two regions from the two proteins share a minimum of 70% overlap). Download the CIF file (.cif)
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