Database accession: MF7000892
Name: Triose-phosphate isomerase (Leishmania mexicana)
PDB ID: 1amk
Experimental method: X-ray (1.83 Å)
Assembly: Homodimer
Source organism: Leishmania mexicana
Primary publication of the structure:
Williams JC, Zeelen JP, Neubauer G, Vriend G, Backmann J, Michels PA, Lambeir AM, Wierenga RK
Structural and mutagenesis studies of leishmania triosephosphate isomerase: a point mutation can convert a mesophilic enzyme into a superstable enzyme without losing catalytic power.
(1999) Protein Eng. 12: 243-50
PMID: 10235625
Abstract:
The dimeric enzyme triosephosphate isomerase (TIM) has a very tight and rigid dimer interface. At this interface a critical hydrogen bond is formed between the main chain oxygen atom of the catalytic residue Lys13 and the completely buried side chain of Gln65 (of the same subunit). The sequence of Leishmania mexicana TIM, closely related to Trypanosoma brucei TIM (68% sequence identity), shows that this highly conserved glutamine has been replaced by a glutamate. Therefore, the 1.8 A crystal structure of leishmania TIM (at pH 5.9) was determined. The comparison with the structure of trypanosomal TIM shows no rearrangements in the vicinity of Glu65, suggesting that its side chain is protonated and is hydrogen bonded to the main chain oxygen of Lys13. Ionization of this glutamic acid side chain causes a pH-dependent decrease in the thermal stability of leishmania TIM. The presence of this glutamate, also in its protonated state, disrupts to some extent the conserved hydrogen bond network, as seen in all other TIMs. Restoration of the hydrogen bonding network by its mutation to glutamine in the E65Q variant of leishmania TIM results in much higher stability; for example, at pH 7, the apparent melting temperature increases by 26 degrees C (57 degrees C for leishmania TIM to 83 degrees C for the E65Q variant). This mutation does not affect the kinetic properties, showing that even point mutations can convert a mesophilic enzyme into a superstable enzyme without losing catalytic power at the mesophilic temperature.
Annotations from the GeneOntology database. Only terms that fit at least two of the interacting proteins are shown. Molecular function:
triose-phosphate isomerase activity triose-phosphate isomerase activity
Biological process:
gluconeogenesis gluconeogenesis
glyceraldehyde-3-phosphate biosynthetic process glyceraldehyde-3-phosphate biosynthetic process
glycerol catabolic process glycerol catabolic process
glycolytic process glycolytic process
Cellular component:
cytosol cytosol
glycosome glycosome
Structural annotations of the participating protein chains.Entry contents: 2 distinct polypeptide molecules
Chains: A, A-2
Notes: All chains according to the most probable oligomerization state stored in PDBe were considered.
Number of unique protein segments: 1
Name: Triosephosphate isomerase
Source organism: Leishmania mexicana
Length: 251 residues
Sequence:Sequence according to the corresponding UniProt protein segmentMSAKPQPIAAANWKCNGTTASIEKLVQVFNEHTISHDVQCVVAPTFVHIPLVQAKLRNPKYVISAENAIAKSGAFTGEVSMPILKDIGVHWVILGHSERRTYYGETDEIVAQKVSEACKQGFMVIACIGETLQQREANQTAKVVLSQTSAIAAKLTKDAWNQVVLAYEPVWAIGTGKVATPEQAQEVHLLLRKWVSENIGTDVAAKLRILYGGSVNAANAATLYAKPDINGFLVGGASLKPEFRDIIDATR
UniProtKB AC: P48499 (positions: 2-251)
Coverage: 99%
Name: Triosephosphate isomerase
Source organism: Leishmania mexicana
Length: 251 residues
Sequence:Sequence according to the corresponding UniProt protein segmentMSAKPQPIAAANWKCNGTTASIEKLVQVFNEHTISHDVQCVVAPTFVHIPLVQAKLRNPKYVISAENAIAKSGAFTGEVSMPILKDIGVHWVILGHSERRTYYGETDEIVAQKVSEACKQGFMVIACIGETLQQREANQTAKVVLSQTSAIAAKLTKDAWNQVVLAYEPVWAIGTGKVATPEQAQEVHLLLRKWVSENIGTDVAAKLRILYGGSVNAANAATLYAKPDINGFLVGGASLKPEFRDIIDATR
UniProtKB AC: P48499 (positions: 2-251)
Coverage: 99%
Evidence demonstrating that the participating proteins are unstructured prior to the interaction and their folding is coupled to binding. Representative domain in related structures: Triosephosphate isomerase
Evidence level: Direct evidence
Evidence coverage: The full structure participates in mutual synergistic folding.
Complex Evidence:
Two-state unfolding behavior was proved experimentally for sveral members of the family. Isolated monomers are not stable at all. (PMID:15037083, PMID:10785370, PMID:26206330).
Chain A:
N/A
Chain A-2:
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)
Download this entry's XML file (.xml)
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