We are interested in studying novel functions of proteins related to ubiquitin. We also aim to identify and study novel proteins related to ubiquitin. Initially we plan to understand roles of these proteins in cellular processes like RNA splicing and stress signaling. For these goals we perform experiments in cell biology, genetics, and biochemistry in the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe. We aim to utilize mammalian cell cultures and multi-cellular organisms through collaborations - to address questions related to the conservation of functions and application of our studies.
Ubiquitin and ubiquitin-like modifiers, for example, Hub1, SUMO, NEDD8 etc. (referred together as UBL) are a group of small proteins with ubiquitin fold and function as central regulators of a vast number of cellular processes. Covalent attachment of ubiquitin to a target protein requires a set of dedicated enzymes (the process is called ubiquitination). This process determines fate of the targets through proteasomal degradation. However, ubiquitination also confers functional diversity to its targets in non-proteolytic ways and is known to play key roles in various cellular processes like DNA repair, signal transduction, protein sorting etc. In contrast most ubiquitin-like proteins function as non-destructive tags, which are known to play regulatory roles in large number of processes in the cell.
UBLs also have the ability to act non-covalently. A notable example is Hub1 which lacks the potential for covalent conjugation and functions in RNA splicing in a unique way - efficient splicing of a subset of introns and a class of alternative splicing events require non-covalent modification of the splicing machinery (spliceosome) by Hub1.
- Ammon, T., Mishra, S.K., Kowalska, K., Popowicz, G.M., Holak, T., and Jentsch, S. (2014). The conserved ubiquitin-like protein Hub1 plays a critical role in splicing in human cells. J. Mol. Cell Biol. 6: 312-323.
- Mishra, S.K., Ammon, T., Popowicz, G.M., Krajewski, M., Nagel, R.J., Ares, M., Holak, T., and Jentsch, S. (2011). Role of the ubiquitin-like protein Hub1 in splice-site usage and alternative splicing. Nature (Article) 474: 173-178.
- Mishra, S.K., Tripp, J., Winkelhaus, S., Tschiersch, B., Theres, K., Nover, L., and Scharf, K.-D. (2002). In the complex family of heat stress transcription factors, HsfA1 has a unique role as master regulator of thermo tolerance in tomato. Genes & Dev. 16: 1555-1567.
- Tripp, J*., Mishra, S.K*., and Scharf, K.-D. (2009). Functional dissection of the cytosolic chaperone network in tomato mesophyll protoplasts. Plant Cell Environ. 32: 123-133. (*Equal contribution).
- Baniwal, S.K., Bharti, K., Chan, K.Y., Fauth, M., Ganguli, A., Kotak, S., Mishra, S.K., Nover, L., Port, M., Scharf, K.-D., Tripp, J., Zielinski, D., and von Koskull-Doering, P. (2004). Heat stress response in plants: a complex game with chaperones and more than 20 heat stress transcription factors. J. Biosci. 29: 471-487 (Review).
- Nover, L., Bharti, K., Doering, P., Mishra, S.K., Ganguli, A., and Scharf, K.-D. (2001). Arabidopsis and the heat stress transcription factor world: how many heat stress transcription factors do we need? Cell Stress Chap. 6: 177-189 (Review).