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PDBsum entry 2pqh
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Structural protein
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PDB id
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2pqh
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References listed in PDB file
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Key reference
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Title
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Structure-Function study of maize ribosome-Inactivating protein: implications for the internal inactivation region and the sole glutamate in the active site.
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Authors
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A.N.Mak,
Y.T.Wong,
Y.J.An,
S.S.Cha,
K.H.Sze,
S.W.Au,
K.B.Wong,
P.C.Shaw.
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Ref.
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Nucleic Acids Res, 2007,
35,
6259-6267.
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PubMed id
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Abstract
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Maize 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.
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