Like all living organisms, bacteria need nutrients in their environment to survive and grow. When the survival of bacteria like Bacillus subtilis is threatened by starvation they respond by going into a “hibernation” state by forming spores. The process for producing a spore, called sporulation, is highly complex and requires careful coordination with other cellular processes like DNA replication. To understand how cells are able to orchestrate this coordination, Dr. Oleg Igoshin, an Associate Professor at Rice University partnered with Associate Professor, Gurol Suel from the University of California San Diego to study sporulation of the soil bacterium Bacillus subtilis, a model organism for systems biology research.
Jatin Narula, Anna Kuchina, Dong-Yeon D. Lee, and Masaya Fujita compose the research team, led by Igoshin and Suel, interested in clarifying the genetic mechanism of spore formation or sporulation. By combining experimental methods from systems and synthetic biology with mathematical modeling, the researchers uncovered the coordination mechanism required for sporulation. The modeling predicted that the key to this coordination is the specific arrangement of two pivotal sporulation genes on the bacterial chromosome. This arrangement produces a temporary mismatch in the number of copies of these two genes during DNA replication. This mismatch is detected by the biochemical network controlling sporulation to ensure proper coordination and the completion of DNA replication. These predictions were confirmed when rearrangement of the two pivotal genes on the chromosome prevented cells from sporulating. The sporulation mechanism that Igoshin and his team elucidated is described in the video above and in a recent research article in Cell.
When asked about the broader impacts of this research for cell biology, Igoshin said “We found that the relative arrangement of the two sporulation genes on DNA were similar in more than 40 strains of spore-forming bacteria. This evidence suggests that this timing mechanism is highly conserved, and it is possible that other time-critical functions related to the cell cycle may be regulated in a similar way.”
In addition to the scientific impact of this research, the collaborative nature of the research provided interdisciplinary training for participating graduate students. Furthermore, the innovative approaches used by Igoshin and colleagues may be applicable to similar problems in other organisms and useful for teaching system-level concepts to students of various levels and backgrounds.