Structural highlights
Publication Abstract from PubMedCytokinin (CK)-activating enzyme, called LOG, is a phosphoribohydrolase that hydrolyzes nucleotides into nucleobases and phosphoriboses. This reaction is a fascinating target for regulation of cellular active CK. However, misannotation of LOG as a lysine decarboxylase and the lack of detailed catalytic and substrate-binding mechanisms have prevented studies of LOG at a protein-level. In this study, we determined the crystal structure of PA4923 from Pseudomonas aeruginosa PAO1. The overall structure of PA4923 resembles those of type-I LOGs, and it exhibited phosphoribohydrolase activity against AMP. These observations indicated that PA4923 functions as an LOG. We also determined the PaLOG structure in complex with AMP and elucidated the detailed binding mode of LOG against the AMP substrate. Interestingly, PaLOG undergoes an open/closed conformational change upon binding AMP, during which the Glu74 residue located on the beta3-beta4 connecting loop flips 180 degrees and moves 13 A toward the AMP molecule. Structural and amino acid sequence comparisons of LOGs suggest that this conformational change upon substrate binding might be a common phenomenon in LOGs. In addition, based on our structural studies and the reported catalytic mechanism of nucleoside hydrolases, we proposed a catalytic mechanism for LOG in which an oxocarbenium ion-like transition state is formed. This article is protected by copyright. All rights reserved. Structural insight into molecular mechanism of cytokinin activating protein from Pseudomonas aeruginosa PAO1.,Seo H, Kim KJ Environ Microbiol. 2018 Jun 14. doi: 10.1111/1462-2920.14287. PMID:29901273[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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