3R68 image
Deposition Date 2011-03-21
Release Date 2011-05-18
Last Version Date 2024-02-21
Entry Detail
PDB ID:
3R68
Title:
Molecular Analysis of the PDZ3 domain of PDZK1
Biological Source:
Source Organism:
Mus musculus (Taxon ID: 10090)
Host Organism:
Method Details:
Experimental Method:
Resolution:
1.30 Å
R-Value Free:
0.15
R-Value Work:
0.13
R-Value Observed:
0.13
Space Group:
P 43 21 2
Macromolecular Entities
Polymer Type:polypeptide(L)
Molecule:Na(+)/H(+) exchange regulatory cofactor NHE-RF3
Gene (Uniprot):Pdzk1
Chain IDs:A
Chain Length:95
Number of Molecules:1
Biological Source:Mus musculus
Primary Citation
Identification of the PDZ3 Domain of the Adaptor Protein PDZK1 as a Second, Physiologically Functional Binding Site for the C Terminus of the High Density Lipoprotein Receptor Scavenger Receptor Class B Type I.
J.Biol.Chem. 286 25171 25186 (2011)
PMID: 21602281 DOI: 10.1074/jbc.M111.242362

Abstact

The normal expression, cell surface localization, and function of the murine high density lipoprotein receptor scavenger receptor class B type I (SR-BI) in hepatocytes in vivo, and thus normal lipoprotein metabolism, depend on its four PDZ domain (PDZ1-PDZ4) containing cytoplasmic adaptor protein PDZK1. Previous studies showed that the C terminus of SR-BI ("target peptide") binds directly to PDZ1 and influences hepatic SR-BI protein expression. Unexpectedly an inactivating mutation in PDZ1 (Tyr(20) → Ala) only partially, rather than completely, suppresses the ability of PDZK1 to control hepatic SR-BI. We used isothermal titration calorimetry to show that PDZ3, but not PDZ2 or PDZ4, can also bind the target peptide (K(d) = 37.0 μm), albeit with ∼10-fold lower affinity than PDZ1. This binding is abrogated by a Tyr(253) → Ala substitution. Comparison of the 1.5-Å resolution crystal structure of PDZ3 with its bound target peptide ((505)QEAKL(509)) to that of peptide-bound PDZ1 indicated fewer target peptide stabilizing atomic interactions (hydrogen bonds and hydrophobic interactions) in PDZ3. A double (Tyr(20) → Ala (PDZ1) + Tyr(253) → Ala (PDZ3)) substitution abrogated all target peptide binding to PDZK1. In vivo hepatic expression of a singly substituted (Tyr(253) → Ala (PDZ3)) PDZK1 transgene (Tg) was able to correct all of the SR-BI-related defects in PDZK1 knock-out mice, whereas the doubly substituted [Tyr(20) → Ala (PDZ1) + Tyr(253) → Ala (PDZ3)]Tg was unable to correct these defects. Thus, we conclude that PDZK1-mediated control of hepatic SR-BI requires direct binding of the SR-BI C terminus to either the PDZ1 or PDZ3 domains, and that binding to both domains simultaneously is not required for PDZK1 control of hepatic SR-BI.

Legend

Protein

Chemical

Disease

Primary Citation of related structures