The SH3 domain of HS1 protein recognizes lysine-rich polyproline motifs

DOI: 10.1007/s00726-011-0831-4
PMID: 21287358

Authors: Guiliano Siligardi (Diamond Light Source) , Paolo Ruzza (Institute of Biomolecular Chemistry of CNR,) , Rohanah Hussain (Diamond Light Source) , Luca Cesaro (University of Padova) , Anna Maria Brunati (University of Padova) , Lorenzo Pinna (University of Padova) , Arianna Donella-deana (University of Padova)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Amino Acids , VOL 42 (4)

State: Published (Approved)
Published: January 2011
Diamond Proposal Number(s): 2023

Abstract: HS1 is a protein involved in erythroid proliferation and apoptotic cell death, containing several structurally significant motifs including a C-terminal SH3 domain. HPK1 is a member of the Ste20-related kinase family, which contains four proline-rich sequences and is constitutively associated with HS1 in hematopoietic cells. Recombinant fusion protein GST-SH3HS1 was expressed to assess the binding properties of 16 peptides derived from the HPK1 proline-rich regions. The binding affinities were determined by non-immobilized ligand interaction assay by circular dichroism. Our results revealed that the classical PxxPxK class II binding motif is not sufficient to induce the interaction with the GST-SH3HS1 domain, an event dependent on the presence of additional basic residue(s) located at the C-terminus of the PxxPxK motif: Lys?5 in P2 peptide and Lys?8 in P4c peptide. Lys replacement by Arg residues decreases the ligand binding affinity. The finding that both SH3HS1 domain and full-length HS1 protein bind to P2 peptide with similar affinity demonstrates that the whole protein sequence does not affect the interaction properties of the domain. In silico models of SH3HS1 as a complex with P2 or P4c highlight the domain residues that interact with the recognition determinants of the peptide ligand and that cooperate in the complex stabilization.

Journal Keywords: Hs1; Pro-Rich Peptides; Sh3 Domain; Protein–Protein Interaction

Subject Areas: Biology and Bio-materials, Medicine, Chemistry


Instruments: B23-Circular Dichroism