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Tuesday, August 4, 2020

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Biochemists left cell-shocked by UH study


Associate professor Masaya Fujita and doctoral candidate Sarem Davi study B. subtilis cells grown on an agar plate. | File photo/The Daily Cougar

Novel research in UH’s biochemistry department is unfolding previously misunderstood and seemingly simple pathways in bacterial sporulation.

Biochemistry associate professor Masaya Fujita and doctoral candidate Sarem Davi recently published a paper in Proceedings of the National Academy of Sciences that outlines a mechanism for spore formation in bacillus subtilis, a common bacteria that is harmless to humans. The pathway was previously assumed by other scientists to involve only one protein: Spo0A. Fujita and Davi discovered that multiple checkpoints were involved that caused this bacteria to form into a spore.

“For the bacterial system, people thought it was much simpler than a eukaryotic system. Of course, the eukaryotic systems like our body are very complicated and have checkpoints or critical points to decide their future fate,” Fujita said.

“However, B. subtilis undergoes either a growing cell or a spore, depending on the environmental conditions. It’s just two choices so people thought that this was very simple: that a single protein Spo0A molecule can make these decisions. However, the cells expressing Spo0A only kick off the sporulation process and begin making preparations, but the cells are not yet committed to this survival strategy.”

The research was published in the PNAS journal because of the surprise that the previous assumptions were debunked, Fujita said. Instead of a simple network, the process involves many different steps.

The research team found that the ultimate decision process for sporulation is a result of a series of nested “feed forward” loops — network motifs in which one master regulator controls another by directly regulating its amount and indirectly regulating its activity, Fujita said.

“Using such integrated and sophisticated genetic networks, the cells can process information, and if needed, change their mind, though without a brain. This strategy allows them to make an accurate decision under unpredictable environmental conditions. Thus, the cells can postpone their final decision-making until the point of no return.”

This process is difficult to study with in the wild B. subtilis, Davi said. Artificial techniques needed to be used to study the processes.

“It’s very difficult to study in the wild-type cells so that’s why we use this artificial sporulation system so we can decouple the pathways. We can dissect different pathways and use IPCT as the inducer to study different parts. We can study it in more detail. That is how we can find out that there are different steps going on. It’s very complex,” Davi said.

Davi, who is starting her fourth year in her doctoral program, said she hopes to graduate with this paper.

More information about biology and biochemistry can be found at www.bchs.uh.edu.

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