| Structural highlights
Function
[SPY_ECOLI] An ATP-independent periplasmic chaperone, decreases protein aggregation and helps protein refolding. Binds substrate over a large region of its convex inner surface (PubMed:21317898, PubMed:24497545). Substrate protein folds while it is bound to chaperone (PubMed:26619265). Increasing Spy flexibility increases its substrate affinity and overall chaperone activity (shown for 3 different substrates) (PubMed:24497545). Protects proteins in vitro against tannin inactivation; tannins have antimicrobial activity (PubMed:21317898). Overexpression enhances the stability of otherwise unstable periplasmic proteins (PubMed:21317898).[1] [2] [3] [IMM7_ECOLX] This protein is able to protect a cell, which harbors the plasmid ColE7 encoding colicin E7, against colicin E7, it binds specifically to the DNase-type colicin and inhibits its bactericidal activity. Dimeric ImmE7 may possess a RNase activity that cleaves its own mRNA at a specific site and thus autoregulates translational expression of the downstream ceiE7 gene as well as degradation of the upstream ceaE7 mRNA.
Publication Abstract from PubMed
Challenges in determining the structures of heterogeneous and dynamic protein complexes have greatly hampered past efforts to obtain a mechanistic understanding of many important biological processes. One such process is chaperone-assisted protein folding. Obtaining structural ensembles of chaperone-substrate complexes would ultimately reveal how chaperones help proteins fold into their native state. To address this problem, we devised a new structural biology approach based on X-ray crystallography, termed residual electron and anomalous density (READ). READ enabled us to visualize even sparsely populated conformations of the substrate protein immunity protein 7 (Im7) in complex with the Escherichia coli chaperone Spy, and to capture a series of snapshots depicting the various folding states of Im7 bound to Spy. The ensemble shows that Spy-associated Im7 samples conformations ranging from unfolded to partially folded to native-like states and reveals how a substrate can explore its folding landscape while being bound to a chaperone.
Visualizing chaperone-assisted protein folding.,Horowitz S, Salmon L, Koldewey P, Ahlstrom LS, Martin R, Quan S, Afonine PV, van den Bedem H, Wang L, Xu Q, Trievel RC, Brooks CL 3rd, Bardwell JC Nat Struct Mol Biol. 2016 May 30. doi: 10.1038/nsmb.3237. PMID:27239796[4]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Quan S, Koldewey P, Tapley T, Kirsch N, Ruane KM, Pfizenmaier J, Shi R, Hofmann S, Foit L, Ren G, Jakob U, Xu Z, Cygler M, Bardwell JC. Genetic selection designed to stabilize proteins uncovers a chaperone called Spy. Nat Struct Mol Biol. 2011 Feb 13. PMID:21317898 doi:10.1038/nsmb.2016
- ↑ Quan S, Wang L, Petrotchenko EV, Makepeace KA, Horowitz S, Yang J, Zhang Y, Borchers CH, Bardwell JC. Super Spy variants implicate flexibility in chaperone action. Elife. 2014;3:e01584. doi: 10.7554/eLife.01584. Epub 2014 Feb 4. PMID:24497545 doi:http://dx.doi.org/10.7554/eLife.01584
- ↑ Stull F, Koldewey P, Humes JR, Radford SE, Bardwell JC. Substrate protein folds while it is bound to the ATP-independent chaperone Spy. Nat Struct Mol Biol. 2016 Jan;23(1):53-8. doi: 10.1038/nsmb.3133. Epub 2015 Nov, 30. PMID:26619265 doi:http://dx.doi.org/10.1038/nsmb.3133
- ↑ Horowitz S, Salmon L, Koldewey P, Ahlstrom LS, Martin R, Quan S, Afonine PV, van den Bedem H, Wang L, Xu Q, Trievel RC, Brooks CL 3rd, Bardwell JC. Visualizing chaperone-assisted protein folding. Nat Struct Mol Biol. 2016 May 30. doi: 10.1038/nsmb.3237. PMID:27239796 doi:http://dx.doi.org/10.1038/nsmb.3237
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