Journal: Oncotarget
Article Title: The discovery of potent ribosomal S6 kinase inhibitors by high-throughput screening and structure-guided drug design
doi:
Figure Lengend Snippet: A) Superposition of the staurosporine-bound structures of PKA (PDB code: 1STC) in light green and the PKA-S6K1 chimera in light blue showing the close similarity of the structures. The inhibitor peptide PKI is shown in yellow and blue in the respective structures. The staurosporine molecules are shown in cylinder representation. Relevant secondary structure elements are labelled. B) Superposition of the staurosporine-bound structures of the PKA-S6K1 chimera in light blue and native S6K1 (PDB code: 3A62) in orange showing the similarity in their tertiary structures and the nearly identical binding mode of staurosporine. The inhibitor peptide PKI present in the PKA-S6K1 chimera structure is shown in blue. C) Close-up of the superposition of the staurosporine bound PKA-S6K1 chimera and the adenosine-bound PKA structure (PDB code: 1BKX) which represents an intermediate conformation in the PKA catalytic cycle. The colour scheme is the same as in panel A, but the adenosine molecule bound in 1BKX is not displayed for clarity. Phe327 in the C -terminal tail and the aromatic residue at the tip of the P-loop (Tyr54/Phe54) adopt different conformations in the respective structures. D) Close-up of the S6K1 and PKA-S6K1 chimera superposition. The positions of four of the five mutations in the PKA-S6K1 chimera ATP-binding site (Tyr54, Leu120, Leu123, Met173) are highlighted using the PKA-S6K1 sequence numbering. The fifth mutation near the ATP-binding site (Lys181) could not be shown in this orientation. Also shown is Tyr102 in S6K1. All structural figures were made using CCP4MG .
Article Snippet: Prior to crystallisation, the purified protein was concentrated to 18 mg/mL in crystallisation buffer consisting of 25 mM MES-Bis/Tris pH 6.5, 75 mM LiCl, 0.1 mM EDTA, 1 mM octanoyl- N -methylglucamide and 1 mM DTT and containing 1 mM PKA-inhibitor peptide PKI (residues 5-24, Sigma-Aldrich) or an in-house synthesised peptide corresponding to residues 5-22 of the PKA-inhibitor peptide, but terminating with an amide at the C -terminus.
Techniques: Binding Assay, Sequencing, Mutagenesis
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