Plant cell walls are highly dynamic structures that are composed predominately of polysaccharides. As such, endogenous carbohydrate active enzymes (CAZymes) are central to the synthesis and subsequent modification of plant cells during morphogenesis. The endo-glucanase 16 (EG16) members constitute a distinct group of plant CAZymes, angiosperm orthologs of which were recently shown to have dual β-glucan/xyloglucan hydrolase activity. Molecular phylogeny indicates that EG16 members comprise a sister clade with a deep evolutionary relationship to the widely studied apoplastic xyloglucan endo-transglycosylases/hydrolases (XTH). A cross-genome survey indicated that EG16 members occur as a single ortholog across species and are widespread in early diverging plants, including the non-vascular bryophytes, for which functional data were previously lacking. Remarkably, enzymological characterization of an EG16 ortholog from the model moss Physcomitrella patens (PpEG16) revealed that EG16 activity and sequence/structure are highly conserved across 500 million years of plant evolution, vis-à-vis orthologs from grapevine and poplar. Ex vivo biomechanical assays demonstrated that the application of EG16 gene products caused abrupt breakage of etiolated hypocotyls rather than slow extension, thereby indicating a mode-of-action distinct from endogenous expansins and microbial endo-glucanases. The biochemical data presented here will inform future genomic, genetic, and physiological studies of EG16 enzymes.
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Cover Image
Cover Image
Parp7 is part of an androgen signaling axis that controls its expression in prostate cancer cells. Kamata and colleagues (pp. 2999–3014) show that Parp7 selectively ADP-ribosylates the agonist conformation of the androgen receptor (AR). The cover image shows nuclear localization of Parp7 (red) and AR (green) in prostate cancer cells using confocal scanning microscopy. Co-localization of Parp7 and AR (yellow) and DAPI staining of DNA (blue) is also shown. Image provided by Natalia Dworak, Chun-Song Yang, and Bryce Paschal.
Conservation of endo-glucanase 16 (EG16) activity across highly divergent plant lineages
Hila Behar, Kazune Tamura, Edward R. Wagner, Daniel J. Cosgrove, Harry Brumer; Conservation of endo-glucanase 16 (EG16) activity across highly divergent plant lineages. Biochem J 27 August 2021; 478 (16): 3063–3078. doi: https://doi.org/10.1042/BCJ20210341
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