1pu3
From Proteopedia
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The Solution NMR Structure and Dynamics of a Recombinant Onconase with Altered N-terminal and Met23 residues
Overview
Onconase (rONC), otherwise known as ranpirnase or P-30 protein, which was, initially purified from extracts of Rana pipiens oocytes and early, embryos, exhibits anticancer activity both in vitro and in vivo and is in, phase III clinical trials for tumor therapy. We have determined the, solution NMR structure of a recombinant onconase with Met(-1), Gln1, and, Leu23 residues (M-1, Q1, M23L)rONC. The 20 best solution structures had a, backbone root mean square deviation of 0.41 +/- 0.09 A with respect to the, average structure. The energy-minimized average NMR structure had a, backbone root mean square deviation of 0.72 A from the x-ray, crystallographic structure of native onconase; however, the orientation of, the N-terminal residue in the two structures was very different., Comparison of the 15N HSQC spectrum of (M-1, Q1, M23L)rONC with that of a, mutant E1S-rONC, which is identical to the nONC except with the N-terminal, pyroglutamyl residue replaced by Ser, showed that N-terminal and residue, 23 mutations induced structural changes in regions beyond the mutation, sites. Model-free analysis of the backbone amide 15N-T1, 15N-T2, and, 15N-1H NOE relaxation data for (M-1, Q1, M23L)rONC and E1S-rONC revealed, that the E1S-rONC molecule showed very little flexibility, whereas (M-1, Q1, M23L)rONC exhibited substantial flexibility, which may account for the, previously observed reduced stability and increased protease, susceptibility. The alpha1 helix and beta-sheets of (M-1, Q1, M23L)rONC, displayed bending motions. These data provided strong evidence for the, presence of an N-terminal hydrogen bond network in E1S-rONC, but not in, (M-1, Q1, M23L)rONC.
About this Structure
1PU3 is a Single protein structure of sequence from Rana pipiens. Full crystallographic information is available from OCA.
Reference
Effect of N-terminal and Met23 mutations on the structure and dynamics of onconase., Gorbatyuk VY, Tsai CK, Chang CF, Huang TH, J Biol Chem. 2004 Feb 13;279(7):5772-80. Epub 2003 Nov 26. PMID:14645226
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