Bacteria from the genera Bacillus and Clostridium produce unusually durable endospores that are the infectious agent of Anthrax and Botulism. The phagocytosis-like process of engulfment is the hallmark of endospore formation, as it creates the unique cell within a cell structure that allows spore assembly to occur within the cytoplasm. However, it has remained unclear how bacterial cells evolved the ability to perform engulfment given the simplicity of their cellular machinery and the seemingly insurmountable barrier presented by the cell wall that surrounds bacterial cells. Our studies suggest that membrane migration during engulfment is mediated by one essential protein machinery, the SpoIID/SpoIIM/SpoIIP complex that degrades the bacterial cell wall, plus two partially redundant machineries, the SpoIIQ-SpoIIIAH complex that provides a zipper-like adhesion between the developing cells and peptidoglycan biosynthesis which is essential for membrane migration when SpoIIQ is absent. The final step of engulfment, membrane fission, requires both ongoing peptidoglycan biogenesis and SpoIIIE, which is also required for the final stages of chromosome segregation and septal membrane fission during the asymmetrically positioned cell division event of sporulation. We will take a combined cell biological, genetic and biochemical approach to study the spatial regulation of peptidoglycan degradation and synthesis, the protein-protein interactions that mediate engulfment, and to understand the mechanisms by which bacterial cells catalyze membrane fission and are dynamically organized. Engulfment provides a dispensable system to study cell biological events that are essential for all bacteria, such as protein localization and membrane fusion.

Public Health Relevance

Peptidoglycan hydrolases are found in all bacteria that synthesize peptidoglycan, and are potentially lethal because their activity must be strictly regulated to produce cell lysis. Engulfment provides an ideal system for understanding how bacteria control these potentially lethal enzymes, which are attractive targets for novel antibiotics, and has the potential to identify new drug targets in proteins that remodel bacterial membranes or mediate protein localization.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM057045-15
Application #
8214510
Study Section
Special Emphasis Panel (ZRG1-GGG-A (02))
Program Officer
Ainsztein, Alexandra M
Project Start
1998-01-01
Project End
2014-12-31
Budget Start
2012-01-01
Budget End
2012-12-31
Support Year
15
Fiscal Year
2012
Total Cost
$378,243
Indirect Cost
$128,243
Name
University of California San Diego
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
804355790
City
La Jolla
State
CA
Country
United States
Zip Code
92093
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