1ce3

PUTATIVE ANCESTRAL PROTEIN ENCODED BY A SINGLE SEQUENCE REPEAT OF THE MULTIDOMAIN PROTEINASE INHIBITOR FROM NICOTIANA ALATA

spinqualitylabelsall models 1ce3, 20 NMR models Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1ce3 is a 1 chain structure with sequence from Indian tobacco. Full experimental information is available from OCA. For a guided tour on the structure components use FirstGlance. Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed BACKGROUND: The ornamental tobacco Nicotiana alata produces a series of proteinase inhibitors (PIs) that are derived from a 43 kDa precursor protein, NaProPI. NaProPI contains six highly homologous repeats that fold to generate six separate structural domains, each corresponding to one of the native PIs. An unusual feature of NaProPI is that the structural domains lie across adjacent repeats and that the sixth PI domain is generated from fragments of the first and sixth repeats. Although the homology of the repeats suggests that they may have arisen from gene duplication, the observed folding does not appear to support this. This study of the solution structure of a single NaProPI repeat (aPI1) forms a basis for unravelling the mechanism by which this protein may have evolved. RESULTS: The three-dimensional structure of aPI1 closely resembles the triple-stranded antiparallel beta sheet observed in each of the native PIs. The five-residue sequence Glu-Glu-Lys-Lys-Asn, which forms the linker between the six structural domains in NaProPI, exists as a disordered loop in aPI1. The presence of this loop in aPI1 results in a loss of the characteristically flat and disc-like topography of the native inhibitors. CONCLUSIONS: A single repeat from NaProPI is capable of folding into a compact globular domain that displays native-like PI activity. Consequently, it is possible that a similar single-domain inhibitor represents the ancestral protein from which NaProPI evolved. Structure of a putative ancestral protein encoded by a single sequence repeat from a multidomain proteinase inhibitor gene from Nicotiana alata.,Scanlon MJ, Lee MC, Anderson MA, Craik DJ Structure. 1999 Jul 15;7(7):793-802. PMID:10425681 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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