title: Solution NMR structure of S100B bound to the high-affinity target peptide TRTK-12.
abstract: The solution NMR structure is reported for Ca(2+)-loaded S100B bound to a 12-residue peptide, TRTK-12, from the actin capping protein CapZ (alpha1 or alpha2 subunit, residues 265-276: TRTKIDWNKILS). This peptide was discovered by Dimlich and co-workers by screening a bacteriophage random peptide display library, and it matches exactly the consensus S100B binding sequence ((K/R)(L/I)XWXXIL). As with other S100B target proteins, a calcium-dependent conformational change in S100B is required for TRTK-12 binding. The TRTK-12 peptide is an amphipathic helix (residues W7 to S12) in the S100B-TRTK complex, and helix 4 of S100B is extended by three or four residues upon peptide binding. However, helical TRTK-12 in the S100B-peptide complex is uniquely oriented when compared to the three-dimensional structures of other S100-peptide complexes. The three-dimensional structure of the S100B-TRTK peptide complex illustrates that residues in the S100B binding consensus sequence (K4, I5, W7, I10, L11) are all involved in the S100B-peptide interface, which can explain its orientation in the S100B binding pocket and its relatively high binding affinity. A comparison of the S100B-TRTK peptide structure to the structures of apo- and Ca(2+)-bound S100B illustrates that the binding site of TRTK-12 is buried in apo-S100B, but is exposed in Ca(2+)-bound S100B as necessary to bind the TRTK-12 peptide.
authors.affiliation: Department of Biochemistry and Molecular Biology, School of Medicine, University of Maryland, 108 N. Greene St., Baltimore, MD 21201, USA.
authors.forename: Keith G
authors.initials: KG
authors.lastname: Inman
authors.forename: Ruiqing
authors.initials: R
authors.lastname: Yang
authors.forename: Richard R
authors.initials: RR
authors.lastname: Rustandi
authors.forename: Kristine E
authors.initials: KE
authors.lastname: Miller
authors.forename: Donna M
authors.initials: DM
authors.lastname: Baldisseri
authors.forename: David J
authors.initials: DJ
authors.lastname: Weber
mesh_terms: D000595:Amino Acid Sequence; D002118:Calcium / Q000494:pharmacology; D051347:CapZ Actin Capping Protein; D016384:Consensus Sequence; D020832:EF Hand Motifs; D009682:Magnetic Resonance Spectroscopy; D008840:Microfilament Proteins / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D009124:Muscle Proteins / Q000737:chemistry* / Q000378:metabolism*; D009414:Nerve Growth Factors / Q000737:chemistry* / Q000378:metabolism*; D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D017433:Protein Structure, Secondary / Q000187:drug effects; D021122:Protein Subunits; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins / Q000737:chemistry* / Q000378:metabolism*; D012996:Solutions; D013379:Substrate Specificity; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry / Q000378:metabolism
chemical_list: D051347:CapZ Actin Capping Protein; D008840:Microfilament Proteins; D009124:Muscle Proteins; D009414:Nerve Growth Factors; D010455:Peptides; D021122:Protein Subunits; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins; D012996:Solutions; D016159:Tumor Suppressor Protein p53; D002118:Calcium