P. V. Shivaprasad
NCBS, Bangalore
P. V. Shivaprasad is a plant biologist who uses less-studied plant model systems to understand how phenotypes are regulated by small RNAs and epigenetics. He has extensive training in molecular virology, small RNAs, epigenetics, plant-pathogen interactions and plant development. His lab uses various model systems including rice, its wild relatives, cauliflower and Arabidopsis. He is a recipient of Swiss Society for Phytiatry award (2006) and a Fellow of all three Indian Science academies (IASc, INSA and NASI). He obtained EMBO fellowship during 2006, Ramanujan fellowship during 2013 and also a recipient of C.V. Raman award from Karnataka State Science and technology in 2019. He is currently a Professor and Associate Dean of Research at National Centre for Biological Sciences, Bangalore, India.
Session 1F: Lectures by Fellows/Associates
Chairperson: Anirban Basu, NBRC, Manesar
Histone variant H4.V: A gatekeeper to H4K5Ac marks and salt stress transcriptome
Paralogous variants of canonical histones guide accessibility to DNA and function as additional layers of genome regulation. Across eukaryotes, mechanism of action and functional significance of several variants of core histones are well-known except that of histone H4. We identified a novel variant of H4 (H4.V) expressing tissue-specifically among Oryza genera members including wild and cultivated rice species. This variant mediated specific epigenetic changes contributing to seed development as well as in salt tolerance. H4.V was incorporated to specific chromosomal locations where it blocked deposition of active histone marks. Stress dependent redistribution of H4.V enabled incorporation of active H4 Lysine5 Acetylation (H4K5Ac) marks. Mis-expression of H4.V led to defects in seedling growth, reproductive tissue development and in mounting stress responses. H4.V mediated these alterations by condensing chromatin as seen with cryo-EM structures of reconstituted nucleosomes. These results not only uncovered the presence of a H4 variant among plants, but also of a novel chromatin regulation that might have contributed to the adaptation of semi-aquatic plants to varying levels of water and salt concentrations.