Dataset Information

Multilevel structural characteristics for the natural substrate proteins of bacterial small heat shock proteins.

ABSTRACT: Small heat shock proteins (sHSPs) are ubiquitous molecular chaperones that prevent the aggregation of various non-native proteins and play crucial roles for protein quality control in cells. It is poorly understood what natural substrate proteins, with respect to structural characteristics, are preferentially bound by sHSPs in cells. Here we compared the structural characteristics for the natural substrate proteins of Escherichia coli IbpB and Deinococcus radiodurans Hsp20.2 with the respective bacterial proteome at multiple levels, mainly by using bioinformatics analysis. Data indicate that both IbpB and Hsp20.2 preferentially bind to substrates of high molecular weight or moderate acidity. Surprisingly, their substrates contain abundant charged residues but not abundant hydrophobic residues, thus strongly indicating that ionic interactions other than hydrophobic interactions also play crucial roles for the substrate recognition and binding of sHSPs. Further, secondary structure prediction analysis indicates that the substrates of low percentage of ?-sheets or coils but high percentage of ?-helices are un-favored by both IbpB and Hsp20.2. In addition, IbpB preferentially interacts with multi-domain proteins but unfavorably with ? + ? proteins as revealed by SCOP analysis. Together, our data suggest that bacterial sHSPs, though having broad substrate spectrums, selectively bind to substrates of certain structural features. These structural characteristic elements may substantially participate in the sHSP-substrate interaction and/or increase the aggregation tendency of the substrates, thus making the substrates more preferentially bound by sHSPs.

SUBMITTER: Fu X

PROVIDER: S-EPMC3926747 | biostudies-literature | 2014 Feb

REPOSITORIES: biostudies-literature

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Multilevel structural characteristics for the natural substrate proteins of bacterial small heat shock proteins.

Fu Xinmiao X Chang Zengyi Z Shi Xiaodong X Bu Dongbo D Wang Chao C

Protein science : a publication of the Protein Society 20131216 2

Small heat shock proteins (sHSPs) are ubiquitous molecular chaperones that prevent the aggregation of various non-native proteins and play crucial roles for protein quality control in cells. It is poorly understood what natural substrate proteins, with respect to structural characteristics, are preferentially bound by sHSPs in cells. Here we compared the structural characteristics for the natural substrate proteins of Escherichia coli IbpB and Deinococcus radiodurans Hsp20.2 with the respective ...[more]

PMID: 24318917

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Project description:The small heat shock proteins (sHSPs) are a virtually ubiquitous and diverse group of molecular chaperones that can bind and protect unfolding proteins from irreversible aggregation. It has been suggested that intrinsic disorder of the N-terminal arm (NTA) of sHSPs is important for substrate recognition. To investigate conformations of the NTA that could recognize substrates we performed replica exchange molecular dynamics simulations. Behavior at normal and stress temperatures of the dimeric building blocks of dodecameric HSPs from wheat (Ta16.9) and pea (Ps18.1) were compared because they display high sequence similarity, but Ps18.1 is more efficient in binding specific substrates. In our simulations, the NTAs of the dimer are flexible and dynamic; however, rather than exhibiting highly extended conformations they retain considerable α-helical character and contacts with the conserved α-crystallin domain (ACD). Network analysis and clustering methods reveal that there are two major conformational forms designated either "open" or "closed" based on the relative position of the two NTAs and their hydrophobic solvent accessible surface area. The equilibrium constant for the closed to open transition is significantly different for Ta16.9 and Ps18.1, with the latter showing more open conformations at elevated temperature correlated with its more effective chaperone activity. In addition, the Ps18.1 NTAs have more hydrophobic solvent accessible surface than those of Ta16.9. NTA hydrophobic patches are comparable in size to the area buried in many protein-protein interactions, which would enable sHSPs to bind early unfolding intermediates. Reduced interactions of the Ps18.1 NTAs with each other and with the ACD contribute to the differences in dynamics and hydrophobic surface area of the two sHSPs. These data support a major role for the conformational equilibrium of the NTA in substrate binding and indicate features of the NTA that contribute to sHSP chaperone efficiency.

Dataset Information

Multilevel structural characteristics for the natural substrate proteins of bacterial small heat shock proteins.

Publications

Multilevel structural characteristics for the natural substrate proteins of bacterial small heat shock proteins.

Similar Datasets

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