Title: Allostery between two binding sites in the ion channel subunit TRIP8b confers binding specificity to HCN channels
Authors: Lyman, Kyle A
Han, Ye
Heuermann, Robert J
Cheng, Xiangying
Kurz, Jonathan E
Lyman, Reagan E
Van Veldhoven, Paul P
Chetkovich, Dane M # ×
Issue Date: Oct-2017
Publisher: American Society for Biochemistry and Molecular Biology
Series Title: Journal of Biological Chemistry vol:292 issue:43 pages:17718-17730
Article number: jbc.M117.802256
Abstract: Tetratricopeptide repeat (TPR) domains are ubiquitous structural motifs that mediate protein-protein interactions. For example, the TPR domains in the peroxisomal import receptor PEX5 enable binding to a range of type 1 peroxisomal targeting signal (PTS1) motifs. A homolog of PEX5, tetratricopeptide repeat-containing Rab8b interacting protein (TRIP8b), binds to and functions as an auxiliary subunit of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. Given the similarity between TRIP8b and PEX5, this difference in function raises the question of what mechanism accounts for their binding specificity. In this report, we found that the cyclic nucleotide-binding domain (CNBD) and the C-terminus of the HCN channel are critical for conferring specificity to TRIP8b binding. We show that TRIP8b binds the HCN CNBD through a 37-residue domain and the HCN C-terminus through the TPR domains. Using a combination of fluorescence polarization and co-immunoprecipitation based assays, we establish that binding at either site increases affinity at the other. Thus, allosteric coupling of the TRIP8b TPR domains both promotes binding to HCN channels and limits binding to PTS1 substrates. These results raise the possibility that other TPR domains may similarly be influenced by allosteric mechanisms as a general feature of protein-protein interactions.
ISSN: 0021-9258
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Laboratory of Lipid Biochemistry and Protein Interactions
× corresponding author
# (joint) last author

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