2pqj

From Proteopedia

Revision as of 16:32, 21 February 2008

Crystal structure of active ribosome inactivating protein from maize (b-32), complex with adenine

Overview

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.

About this Structure

2PQJ is a Single protein structure of sequence from Zea mays with as ligand. Active as rRNA N-glycosylase, with EC number 3.2.2.22 Known structural/functional Sites: , and . Full crystallographic information is available from OCA.

Reference

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

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