title: Mapping of the binding sites involved in PSP94-CRISP-3 interaction by molecular dissection of the complex.
abstract: BACKGROUND
  Human Prostate Secretory Protein of 94 amino acids (PSP94) has been shown to bind human CRISP-3 (cysteine-rich secretory protein 3) with very high affinity. CRISP-3 belongs to the CRISP family of proteins having a PR-1 (pathogenesis related protein 1) domain at its N-terminal and ion channel regulatory (ICR) domain at its C-terminal connected by a hinge region. Functional significance of this complex is not yet known.
  
  
  METHODS
  In order to identify the residues and/or regions involved in PSP94-CRISP-3 interaction, site-directed mutagenesis was employed. Effect of the mutations on the interaction was studied by co-immunoprecipitation (Co-IP).
  
  
  RESULTS
  For PSP94, amino acids Y(3), F(4), P(56) and the C-terminal β-strand were found to be crucial for interacting with CRISP-3. A disulfide bond between the two domains of PSP94 (C(37)A-C(73)A) was also important for this interaction. In case of CRISP-3, the N-terminal domain alone could not maintain a strong interaction with PSP94 but it required presence of the hinge region and not the C-terminal domain. Apart from CRISP-3, CRISP-2 was also found to interact with human PSP94. Based on our findings the most likely model of PSP94-CRISP-3 complex has been proposed.
  
  
  CONCLUSIONS
  The terminal β-strands of PSP94 contact the first α-helix and the hinge region of CRISP-3.
  
  
  CONCLUSIONS
  Involvement of the hinge region of CRISPs in interaction with PSP94 may affect the domain movement of CRISPs essential for the ion-channel regulatory activity resulting in inhibition of this activity.
authors: Division of Structural Biology, National Institute for Research in Reproductive Health, Indian Council of Medical Research, Parel, Mumbai - 400012, India.
authors: Ananya A
authors: AA
authors: Breed
authors: Amanda
authors: A
authors: Gomes
authors: Binita Sur
authors: BS
authors: Roy
authors: Smita D
authors: SD
authors: Mahale
authors: Bhakti R
authors: BR
authors: Pathak
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D045744:Cell Line, Tumor; D006801:Humans; D008297:Male; D008958:Models, Molecular; D008969:Molecular Sequence Data; D029584:Prostatic Secretory Proteins / Q000737:chemistry*; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012471:Salivary Proteins and Peptides / Q000737:chemistry*; D029589:Seminal Plasma Proteins / Q000737:chemistry*
chemical_list: C489926:CRISP3 protein, human; D029584:Prostatic Secretory Proteins; D012471:Salivary Proteins and Peptides; D029589:Seminal Plasma Proteins; C043076:beta-microseminoprotein