7jn9
From Proteopedia
Crystal structure of the substrate-binding domain of E. coli DnaK in complex with the peptide QEHTGSQLRIAAYGP
Structural highlights
FunctionDNAK_ECOLI Plays an essential role in the initiation of phage lambda DNA replication, where it acts in an ATP-dependent fashion with the DnaJ protein to release lambda O and P proteins from the preprimosomal complex. DnaK is also involved in chromosomal DNA replication, possibly through an analogous interaction with the DnaA protein. Also participates actively in the response to hyperosmotic shock.[HAMAP-Rule:MF_00332] Publication Abstract from PubMedHeat shock protein 70 (Hsp70) chaperones bind many different sequences and discriminate between incompletely folded and folded clients. Most research into the origins of this "selective promiscuity" has relied on short peptides as substrates to dissect the binding, but much less is known about how Hsp70s bind full-length client proteins. Here, we connect detailed structural analyses of complexes between the Escherichia coli Hsp70 (DnaK) substrate-binding domain (SBD) and peptides encompassing five potential binding sites in the precursor to E. coli alkaline phosphatase (proPhoA) with SBD binding to full-length unfolded proPhoA. Analysis of SBD complexes with proPhoA peptides by a combination of X-ray crystallography, methyl-transverse relaxation optimized spectroscopy (methyl-TROSY), and paramagnetic relaxation enhancement (PRE) NMR and chemical cross-linking experiments provided detailed descriptions of their binding modes. Importantly, many sequences populate multiple SBD binding modes, including both the canonical N to C orientation and a C to N orientation. The favored peptide binding mode optimizes substrate residue side-chain compatibility with the SBD binding pockets independent of backbone orientation. Relating these results to the binding of the SBD to full-length proPhoA, we observe that multiple chaperones may bind to the protein substrate, and the binding sites, well separated in the proPhoA sequence, behave independently. The hierarchy of chaperone binding to sites on the protein was generally consistent with the apparent binding affinities observed for the peptides corresponding to these sites. Functionally, these results reveal that Hsp70s "read" sequences without regard to the backbone direction and that both binding orientations must be considered in current predictive algorithms. Selective promiscuity in the binding of E. coli Hsp70 to an unfolded protein.,Clerico EM, Pozhidaeva AK, Jansen RM, Ozden C, Tilitsky JM, Gierasch LM Proc Natl Acad Sci U S A. 2021 Oct 12;118(41):e2016962118. doi: , 10.1073/pnas.2016962118. PMID:34625496[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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