Spatial Organization of Biological Fuctions | BPS Thematic Meeting

Spatial Organization of Biological Functions Meeting

Wednesday Speaker Abstracts

EMERGENCE OF SPATIAL PATTERNS IN KINESIN-1 GLIDING ASSAYS Jashaswi Basu 1 ; Chaitanya A Athale 1 ; 1 Indian Institute of Science Education and Research Pune, Biology, Pune, India Kinesin-1, the plus end directed microtubule associated motor protein, has a distinct head catalytic domain and an ATP-independent microtubule (MT) binding tail. The MT binding property of the kinesin-1 tail, along with the head, has been reported to regulate a number of physiological processes like Drosophila ooplasmic streaming and neuronal growth. While single molecule and collective gliding assays have helped us study motor mediated transport extensively, the biophysical properties of the microtubule binding tail in the context of MT binding and transport is less well known. In this study, we proceeded to address this by purifying bacterially expressed constructs of Drosophila kinesin-1 full length and truncated motor domain. In vitro microtubule gliding assays driven by the full length kinesin-1 with both head and tail domains showed microtubules to result in the emergence of multiple patterns such as: (a) transient bending, (b) oscillations and (c) spirals along with linear transport. However, microtubules driven by only the truncated motor domain showed straight and processive gliding motility. The emergence of these patterns we hypothesize could emerge from the precise role of MT binding to the motor tail. In future, using a combination of genetic engineering, collective gliding assays and simulations we hope to understand this better. ACTIN WAVES GUIDE AN OUTWARD MOVEMENT OF MICROCLUSTERS IN THE LYMPHOCYTE IMMUNOLOGICAL SYNAPSE Aheria Dey 1 ; 1 Indian Institute of Science, Department of Microbiology and Cell Biology, Bangalore, India 2 Indian Institute of Science, Department of Physics, Bangalore, India 3 University of Oxford, Oxfordshire, United Kingdom The lymphocyte immune response begins with antigen recognition on antigen-presenting cells, leading to the formation of the immunological synapse—a specialized interface for biochemical and biophysical exchange. At the synapse, most antigen-engaged receptor microclusters move inward toward the central supramolecular activation cluster (cSMAC) via retrograde F-actin flow, eventually clearing from the cell surface. This retrograde movement and receptor downregulation maintain antigen receptor homeostasis, critical for adaptive immunity, though its regulation remains unclear. Using live T cells, we identified a significant pool of antigen engaged microclusters moving anterogradely toward the cell periphery, rather than the cSMAC. This movement was driven by actin waves propagating outward and coupling to microclusters through the Wiskott-Aldrich Syndrome Protein. These findings reveal a previously unrecognized mode of actin dynamics—anterograde actin waves—that co-exist with retrograde flow and direct microclusters away from the downregulation zone. This dual actin behavior underscores the complex cytoskeletal mechanisms T cells employ to regulate receptor distribution and maintain signaling homeostasis during immune activation.

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