2pqj
Crystal structure of active ribosome inactivating protein from maize (b-32), complex with adenine
Structural highlights
FunctionRIP3_MAIZE Possesses features of some constitutive defense agent. The coordinate Opaque-2-controlled synthesis of this protein and the major seed storage proteins (zeins) may provide the germinating seedling with both nutritional benefits and protection against pathogen invasion of the surrounding endosperm. 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 PubMedMaize ribosome-inactivating protein is classified as a class III or an atypical RNA N-glycosidase. It is synthesized as an inactive precursor with a 25-amino acid internal inactivation region, which is removed in the active form. As the first structural example of this class of proteins, crystals of the precursor and the active form were diffracted to 2.4 and 2.5 A, respectively. The two proteins are similar, with main chain root mean square deviation (RMSD) of 0.519. In the precursor, the inactivation region is found on the protein surface and consists of a flexible loop followed by a long alpha-helix. This region diminished both the interaction with ribosome and cytotoxicity, but not cellular uptake. Like bacterial ribosome-inactivating proteins, maize ribosome-inactivating protein does not have a back-up glutamate in the active site, which helps the protein to retain some activity if the catalytic glutamate is mutated. The structure reveals that the active site is too small to accommodate two glutamate residues. Our structure suggests that maize ribosome-inactivating protein may represent an intermediate product in the evolution of ribosome-inactivating proteins. Structure-function study of maize ribosome-inactivating protein: implications for the internal inactivation region and the sole glutamate in the active site.,Mak AN, Wong YT, An YJ, Cha SS, Sze KH, Au SW, Wong KB, Shaw PC Nucleic Acids Res. 2007;35(18):6259-67. Epub 2007 Sep 13. PMID:17855394[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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