Abstract:

Cytokinesis is the crucial step of physically partitioning the daughter cells after the duplication and segregation of the genetic material. Bacteria assemble a cytokinetic ring called a Z-ring formed the tubulin homologue, FtsZ. The precise mechanism by which the ring is assembled remains to be completely understood. Traditional mutational approaches have yielded a deep but limited understanding of the Z-ring assembly and is limited by the lethality of the FtsZ mutations in bacteria. We had earlier used a eukaryotic heterologous host Schizosaccharomyces pombe, to study FtsZ ring assembly and showed that the ring assembles by spooling a linear filament. We have further utilized the system to screen for mutants defective in Z-ring assembly and identified several mutants. In this talk, I will focus on two mutants that are trapped in a helical conformation and provide insights into the Z-ring assembly process. We show that the mutants trapped in helical conformations are defective in nucleotide hydrolysis and are defective in lateral association of filaments and ring compaction. Together with physical modelling of ring assembly by a treadmilling filament, our results suggest that Z-ring assembly is driven by torsional stress coupled to treadmilling and lateral association among filaments.

About the Speaker:

Dr. Ramanujam Srinivasan did his PhD from the Indian Institute of Science Bengaluru in 2006 and then went on to do his postdoctoral work with Prof. Mohan Balasubramanian at Temasek Life Sciences Laboratory and Mechanobiology Institute Singapore. His interests have been in bacterial cell division and cytoskeletal proteins. He is currently at NISER, Bhubaneswar and his laboratory is interested in understanding plasmid maintenance and bacterial cell division in the enteric bacterium Escherichia coli.