Graduation Year

2022

Document Type

Dissertation

Degree

Ph.D.

Degree Name

Doctor of Philosophy (Ph.D.)

Degree Granting Department

Biology (Cell Biology, Microbiology, Molecular Biology)

Major Professor

Prahathees Eswara, Ph.D.

Committee Member

Lindsey Shaw, Ph.D.

Committee Member

Wendi Yu, Ph.D.

Committee Member

Yu Chen, Ph.D.

Keywords

DNA Damage, MraZ, FtsL, FtsZ, Pbp2B, YneA, RecA

Abstract

Cell division is a complex and highly orchestrated process that requires careful coordination. The process of cell division in prokaryotes primarily occurs via binary fission, where one mother cell becomes two genetically identically and equally sized daughter cells. In most bacteria a key protein, FtsZ, forms a FtsZ ring (Z-ring) to mark the division site and recruit proteins involved in cytokinesis. Whilst much has been learned about the contents and assembly of the divisome in model organisms such as Escherichia coli and Bacillus subtilis factors governing the regulation of divisome are much more poorly understood. One area of the genome encoding many important cell division factors, including FtsZ, is known as the division and cell wall cluster (dcw). The very first gene of this region is mraZ a highly conserved DNA binding protein. In this dissertation we explore the role of MraZ primarily in B. subtilis and verify whether its function is conserved in a related pathogenic bacterium Staphylococcus aureus. Herein we show that MraZ is a transcriptional repressor of its own operon which includes the essential cell division gene, ftsL. Furthermore, we show that FtsL is required for Z-ring maturation and initiating septal cell wall synthesis. The mra operon was previously shown to be regulated by the replication initiator DnaA during DNA damage. Here we provide evidence that both MraZ and DnaA interact with each other and are required for this repression during DNA damage. Furthermore, our work highlights the importance of both YneA and MraZ (with DnaA) as regulators of FtsL at a post-translational and transcriptional level during DNA Damage. Finally, we provide evidence for post-transcriptional regulation of ftsL by an antisense RNA, S555. Our results show that S555 is important during both salt stress and DNA damage. Taken together, the work in this dissertation shines a light on the key role MraZ plays in transcriptionally regulating the divisome, during both normal growth and times of stress. Additionally, we have been able to pinpoint the role of FtsL for the first time in B. subtilis as coordinating septal peptidoglycan synthesis and aiding in Z-ring maturation. Thus, from this work we have shown that FtsL appears to be the rate-limiting step of cytokinesis and highlighted why this component of the divisome appears to be so highly regulated during stress response as a means to regulate cellular division.

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