2'-O-ribose methylation of transfer RNA promotes recovery from oxidative stress in Saccharomyces cerevisiae.

Chemical modifications that regulate protein expression at the translational level are emerging as vital components of the cellular stress response. Transfer RNAs (tRNAs) are significant targets for methyl-based modifications, which are catalyzed by tRNA methyltransferases (Trms). Here, Saccharomyces cerevisiae served as a model eukaryote system to investigate the role of 2'-O-ribose tRNA methylation in the cell's response to oxidative stress. Using 2'-O-ribose deletion mutants for trms 3, 7, 13, and 44, in acute and chronic exposure settings, we demonstrate a broad cell sensitivity to oxidative stress-inducing toxicants (i.e., hydrogen peroxide, rotenone, and acetic acid). A global analysis of hydrogen peroxide-induced tRNA modifications shows a complex profile of decreased, or undetectable, 2'-O-ribose modification events in 2'-O-ribose trm mutant strains, providing a critical link between this type of modification event and Trm status post-exposure. Based on the pronounced oxidative stress sensitivity observed for trm7 mutants, we used a bioinformatic tool to identify transcripts as candidates for regulation by Trm7-catalyzed modifications (i.e., enriched in UUC codons decoded by tRNAPheGmAA). This screen identified transcripts linked to diverse biological processes that promote cellular recovery after oxidative stress exposure, including DNA repair, chromatin remodeling, and nutrient acquisition (i.e., CRT10, HIR3, HXT2, and GNP1); moreover, these mutants were also oxidative stress-sensitive. Together, these results solidify a role for TRM3, 7, 13, and 44, in the cellular response to oxidative stress, and implicate 2'-O-ribose tRNA modification as an epitranscriptomic strategy for oxidative stress recovery.

Postural asymmetries in response to holding evenly and unevenly distributed loads during self-selected stance.

The authors examined postural asymmetries during quiet stance and while holding evenly or unevenly distributed loads. Right-hand dominant subjects preferentially loaded their right lower limb when holding no load or a load evenly distributed in both hands, but no differences in center of pressure (CoP) were observed between the left and right limbs. However, longer CoP displacement was observed under the preferentially loaded limb, which may reflect a functional asymmetry that allows quick movement of one limb in response to a potential perturbation. When a load was held only in the nondominant hand, sample entropy decreased in the left (loaded) limb but increased in the right (unloaded) limb, suggesting the unloaded foot compensated for a loss of control flexibility in the loaded foot.

Time-to-contact measures capture modulations in posture based on the precision demands of a manual task.

The integration between posture and manual control while performing fitting tasks of varying difficulty was investigated. Participants fit a block into either a small (high precision) or large (low precision) opening while standing on a force plate. Postural time-to-contact was used to quantify changes in posture that occurred during the fitting movement. Results suggest that posture became more stabilized when fitting through the small opening (postural time-to-contact values were higher) compared to when fitting through the large opening. Additionally, when fitting through the small opening, individuals modulated sway based on the instantaneous demands of the task. Specifically, time-to-contact was lower towards the end of a fitting movement (as the individual prepared to fit the block through the opening) compared to the beginning of the movement. These results suggest that the dynamics of postural sway are constantly changing based on the constraints of a concurrent task.