3R68

Molecular Analysis of the PDZ3 domain of PDZK1

Summary for 3R68

• Entry DOI: 10.2210/pdb3r68/pdb
• Related: 2D90 3R69
• Descriptor: Na(+)/H(+) exchange regulatory cofactor NHE-RF3, ACETATE ION, 1,2-ETHANEDIOL, ... (7 entities in total)
• Functional Keywords: pdz domain, adaptor protein, sr-bi, signaling protein
• Biological source: Mus musculus (mouse)
• Cellular location: Cytoplasm: Q9JIL4
• Total number of polymer chains: 1
• Total formula weight: 10940.78

Authors

Kocher, O.,Birrane, G.,Krieger, M. (deposition date: 2011-03-21, release date: 2011-05-18, Last modification date: 2024-02-21)

Primary citation

Kocher, O.,Birrane, G.,Yesilaltay, A.,Shechter, S.,Pal, R.,Daniels, K.,Krieger, M.
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

PubMed Abstract: 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.

PubMed: 21602281
DOI: 10.1074/jbc.M111.242362

Experimental method

X-RAY DIFFRACTION (1.3 Å)