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Solution structure of the human parvulin-like peptidyl prolyl cis/trans isomerase, hPar14
T Terada1, M Shirouzu, Y Fukumori
1Genomic Sciences Center, RIKEN Yokohama Institute, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan.
Abstract:
The hPar14 protein is a peptidyl prolyl cis/trans isomerase and is a human parvulin homologue. The hPar14 protein shows about 30 % sequence identity with the other human parvulin homologue, hPin1. Here, the solution structure of hPar14 was determined by nuclear magnetic resonance spectroscopy. The N-terminal 35 residues preceding the peptidyl prolyl isomerase domain of hPar14 are unstructured, whereas hPin1 possesses the WW domain at its N terminus. The fold of residues 36-131 of hPar14, which comprises a four-stranded beta-sheet and three alpha-helices, is superimposable onto that of the peptidyl prolyl isomerase domain of hPin1. To investigate the interaction of hPar14 with a substrate, the backbone chemical-shift changes of hPar14 were monitored during titration with a tetra peptide. Met90, Val91, and Phe94 around the N terminus of alpha3 showed large chemical-shift changes. These residues form a hydrophobic patch on the molecular surface of hPar14. Two of these residues are conserved and have been shown to interact with the proline residue of the substrate in hPin1. On the other hand, hPar14 lacks the hPin1 positively charged residues (Lys63, Arg68, and Arg69), which determine the substrate specificity of hPin1 by interacting with phosphorylated Ser or Thr preceding the substrate Pro, and exhibits a different structure in the corresponding region. Therefore, the mechanism determining the substrate specificity seems to be different between hPar14 and hPin1.
Insights
The human parvulin homologue, hPar14 protein, has a determined solution structure revealing an unstructured N-terminus and a fold similar to hPin1. Its substrate-binding site differs from hPin1, suggesting distinct specificity mechanisms.
Area of Science:
- Biochemistry
- Structural Biology
- Molecular Biology
Background:
- hPar14 is a human parvulin homologue and peptidyl prolyl cis/trans isomerase.
- It shares approximately 30% sequence identity with another human parvulin homologue, hPin1.
- The structural and functional differences between hPar14 and hPin1 are not fully understood.
Purpose of the Study:
- To determine the solution structure of the hPar14 protein.
- To investigate the substrate-binding interactions of hPar14.
- To compare the structural features and substrate specificity mechanisms of hPar14 with hPin1.
Main Methods:
- Nuclear magnetic resonance (NMR) spectroscopy was used to determine the solution structure of hPar14.
- Backbone chemical-shift changes were monitored during titration with a tetrapeptide to study substrate interaction.
- Structural comparison was made between hPar14 and hPin1.
Main Results:
- The N-terminal 35 residues of hPar14 are unstructured, unlike the WW domain in hPin1.
- The peptidyl prolyl isomerase domain (residues 36-131) of hPar14 folds similarly to hPin1.
- Key residues (Met90, Val91, Phe94) forming a hydrophobic patch were identified as potentially interacting with substrates.
- hPar14 lacks positively charged residues crucial for hPin1's substrate specificity towards phosphorylated substrates.
Conclusions:
- hPar14 possesses a distinct structural organization compared to hPin1, particularly in its N-terminus and substrate-binding region.
- The identified hydrophobic patch in hPar14 suggests a potential substrate interaction site.
- The absence of specific charged residues in hPar14 indicates a different mechanism for substrate specificity compared to hPin1.