title: Heterodimeric interaction and interfaces of S100A1 and S100P.
abstract: With the widespread use of yeast two-hybrid systems, many heterodimeric forms of S100 proteins have been found, although their biological significance is unknown. In the present study, S100A1 was found to interact with another S100 protein, S100P, by using the yeast two-hybrid system. The binding parameters of the interaction were obtained using an optical biosensor and show that S100P has a slightly higher affinity for S100A1 (K(d)=10-20 nM) when compared with that for self-association (K(d)=40-120 nM). The physical interaction of S100A1 and S100P was also demonstrated in living mammalian cells using a fluorescence resonance energy transfer technique. Preincubation of recombinant S100P with S100A1, before the biosensor assay, reduced by up to 50% the binding of S100P to a recombinant C-terminal fragment of non-muscle myosin A, one of its target molecules. Site-specific mutations of S100P and S100A1, combined with homology modelling of an S100P/S100A1 heterodimer using known S100P and S100A1 structures, allowed the hydrophobic interactions at the dimeric interface of the heterodimer to be defined and provide an explanation for the heterodimerization of S100P and S100A1 at the molecular level. These results have revealed the similarities and the differences between the S100P homodimer and the S100A1/S100P heterodimer.
authors.affiliation: Cancer and Polio Research Fund Laboratories Molecular Medicine Group, School of Biological Sciences, Biosciences Building, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK. wangg@liv.ac.uk
authors.forename: Guozheng
authors.initials: G
authors.lastname: Wang
authors.forename: Shu
authors.initials: S
authors.lastname: Zhang
authors.forename: David G
authors.initials: DG
authors.lastname: Fernig
authors.forename: David
authors.initials: D
authors.lastname: Spiller
authors.forename: Marisa
authors.initials: M
authors.lastname: Martin-Fernandez
authors.forename: Hongmei
authors.initials: H
authors.lastname: Zhang
authors.forename: Yi
authors.initials: Y
authors.lastname: Ding
authors.forename: Zihe
authors.initials: Z
authors.lastname: Rao
authors.forename: Philip S
authors.initials: PS
authors.lastname: Rudland
authors.forename: Roger
authors.initials: R
authors.lastname: Barraclough
mesh_terms: D001402:B-Lymphocytes / Q000737:chemistry; D001943:Breast Neoplasms / Q000737:chemistry / Q000473:pathology; D002135:Calcium-Binding Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D045744:Cell Line, Tumor; D003001:Cloning, Molecular; D019281:Dimerization; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods; D049452:Green Fluorescent Proteins / Q000737:chemistry; D006801:Humans; D008958:Models, Molecular; D020409:Molecular Motor Proteins / Q000378:metabolism; D016297:Mutagenesis, Site-Directed / Q000235:genetics; D018995:Myosin Heavy Chains / Q000378:metabolism; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009447:Neuroblastoma / Q000473:pathology; D011485:Protein Binding; D025941:Protein Interaction Mapping; D011994:Recombinant Proteins / Q000378:metabolism; D009418:S100 Proteins; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D020798:Two-Hybrid System Techniques
chemical_list: D002135:Calcium-Binding Proteins; C485182:Cyan Fluorescent Protein; C103814:MYH9 protein, human; D020409:Molecular Motor Proteins; D009363:Neoplasm Proteins; D011994:Recombinant Proteins; D009418:S100 Proteins; C110294:S100A1 protein; C103003:S100P protein, human; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D018995:Myosin Heavy Chains