Biology subjects

Katta, S.

Publications and source records attributed to Katta, S..

4 recordsLinked to original sources

bioRxiv2026

FTO separation-of-function mutations alter m6A versus m6Am demethylation selectivity on RNA

The RNA demethylase FTO erases N6-methyladenosine (m6A) and cap-associated N6,2'-O-dimethyladenosine (m6Am) modifications. However, the molecular basis of its substrate selectivity and the biological effects of m6A versus m6Am demethylation in cells remain poorly understood. Here we report two engineered FTO separation-of-function mutants to selectively demethylate either m6A or m6Am modifications on RNA. While investigating the propensity of FTO active site residues to undergo self-hydroxylation, we found that mutations of FTO residue L203 resulted in impaired m6A demethylation but retained wild-type levels of m6Am demethylation, and that FTO L203A could function as a selective m6Am demethylase. Conversely, building on our recent work that identified conserved aromatic residues on FTO involved in mRNA 5' cap recognition, we found that the FTO H232A/W278A double mutant efficiently demethylates m6A modifications while exhibiting substantially impaired m6Am demethylation, making it a selective m6A demethylase. Together, these complementary FTO variants represent the first set of engineered mutations that shift FTO demethylation selectivity between m6A and m6Am substrates. These tools enable selective enzymatic removal of m6A or m6Am modifications in vitro for sequencing applications, and may facilitate understanding of FTO-mediated m6A versus m6Am demethylation in cellular and disease model systems.

biochemistry↗

bioRxiv2026

KAMALA, a genome edited rice variety with improved yield by finetuning cytokinin oxidase activity released in India

Increasing yield is of major importance for Asian and African food security. Knock out mutants in the rice cytokinin oxidase gene CKX2 had shown potential for yield improvement. Here we explored whether subtle changes in CKX2 activity by editing FAD and cytokinin binding site sequences could improve the Indian mega-variety Samba Mahsuri. Knock out and single mutants in FAD and cytokinin binding sites induced by CRISPR/Cas12a caused moderate yield increases. Among 80 CKX2 alleles, five lines with in-frame mutations in both FAD and cytokinin binding domains produced even higher yield. One line, KAMALA, showed superior agronomic performance in 18 field locations (irrigated and rainfed ecologies) over three seasons in trials conducted by AICRPR (All India Coordinated Research Project on Rice), with an average 19% grain yield increase, early maturity, complete panicle emergence, and unaltered grain quality. KAMALA was registered as the first genome-edited variety ready for cultivation by Indian farmers.

plant biology↗

bioRxiv2019

Progressive recruitment of distal MEC-4 channels determines touch response strength in C. elegans

Touch deforms, or strains, the skin beyond the immediate point of contact. The spatiotemporal nature of the touch-induced strain fields depend on the mechanical properties of the skin and the tissues below. Somatosensory neurons that sense touch branch out within the skin and rely on a set of mechano-electrical transduction channels distributed within their dendrites to detect mechanical stimuli. Here, we sought to understand how tissue mechanics shape touch-induced mechanical strain across the skin over time and how individual channels located in different regions of the strain field contribute to the overall touch response. We leveraged C. elegans touch receptor neurons (TRNs) as a simple model amenable to in vivo whole-cell patch clamp recording and an integrated experimental-computational approach to dissect the mechanisms underlying the spatial and temporal dynamics that we observed. Consistent with the idea that strain is produced at a distance, we show that delivering strong stimuli outside the anatomical extent of the neuron is sufficient to evoke MRCs. The amplitude and kinetics of the MRCs depended on both stimulus displacement and speed. Finally, we found that the main factor responsible for touch sensitivity is the recruitment of progressively more distant channels by stronger stimuli, rather than modulation of channel open probability. This principle may generalize to somatosensory neurons with more complex morphologies.\n\nSummaryThrough experiment and simulation, Katta et al. reveal that pushing faster and deeper recruits more and more distant mechano-electrical transduction channels during touch. The net result is a dynamic receptive field whose size and shape depends on tissue mechanics, stimulus parameters, and channel distribution within sensory neurons.

neuroscience↗

bioRxiv2018

Tissue mechanics and somatosensory neural responses govern touch sensation in C. elegans

The sense of touch hinges on tissues transducing stimuli applied to the skin and somatosensory neurons converting mechanical inputs into currents. Like mammalian Pacinian corpuscles, the light-touch response of the prime model organism C. elegans adapts rapidly, and is symmetrically activated by the onset and offset of a step indentation. Here, we propose a quantitative model that combines transduction of stimuli across the skin and subsequent gating of mechanoelectrical channels. For mechanics, we use an elastic model based on geometrically-nonlinear deformations of a pressurized cylindrical shell. For gating, we build upon consequences of the dermal layers thinness and tangential stimuli. Our model demonstrates how the onset-offset symmetry arises from the coupling of mechanics and adaptation, and accounts for experimental neural responses to a broad variety of stimuli. Predicted effects of modifications in the mechanics or the internal pressure of the body are tested against mechanical and neurophysiological experiments.

neuroscience↗