Epithelial UNC-23 limits mechanical stress to maintain glia-neuron architecture in C. elegans.

For an organ to maintain correct architecture and function, its diverse cellular components must coordinate their size and shape. Although cell-intrinsic mechanisms driving homotypic cell-cell coordination are known, it is unclear how cell shape is regulated across heterotypic cells. We find that epithelial cells maintain the shape of neighboring sense-organ glia-neuron units in adult Caenorhabditis elegans (C. elegans). Hsp co-chaperone UNC-23/BAG2 prevents epithelial cell shape from deforming, and its loss causes head epithelia to stretch aberrantly during animal movement. In the sense-organ glia, amphid sheath (AMsh), this causes progressive fibroblast growth factor receptor (FGFR)-dependent disruption of the glial apical cytoskeleton. Resultant glial cell shape alteration causes concomitant shape change in glia-associated neuron endings. Epithelial UNC-23 maintenance of glia-neuron shape is specific both spatially, within a defined anatomical zone, and temporally, in a developmentally critical period. As all molecular components uncovered are broadly conserved across central and peripheral nervous systems, we posit that epithelia may similarly regulate glia-neuron architecture cross-species.

Quantitative 1H-NMR analysis reveals steric and electronic effects on the substrate specificity of benzoate dioxygenase in Ralstonia eutropha B9.

The cis-dihydroxylation of arenes by Rieske dearomatizing dioxygenases (RDDs) represents a powerful tool for the production of chiral precursors in organic synthesis. Here, the substrate specificity of the RDD benzoate dioxygenase (BZDO) in Ralstonia eutropha B9 whole cells was explored using quantitative 1H nuclear magnetic resonance spectroscopy (q1H-NMR). The specific activity, specific carbon uptake, and regioselectivity of the dihydroxylation reaction were evaluated in resting cell cultures for a panel of 17 monosubstituted benzoates. Two new substrates of this dioxygenase system were identified (2-methyl- and 3-methoxybenzoic acid) and the corresponding cis-diol metabolites were characterized. Higher activities were observed for benzoates with smaller substituents, predominantly at the 3-position. Elevated activities were also observed in substrates bearing greater partial charge at the C-2 position of the benzoate ring. The regioselectivity of the reaction was directly measured using q1H-NMR and found to have positive correlation with increasing substituent size. These results widen the pool of cis-diol metabolites available for synthetic applications and offer a window into the substrate traits that govern specificity for BZDO.