(p)ppGpp in Gram-positive bacteria: stress resistance, homeostasis and evolution

Speaker: Jade Wang, Associate Professor, Dept. of Bacteriology, University of Wisconsin-Madison
Host: Kenn Gerdes, Centre for Bacterial Stress Response and Persistence, UCPH

Abstract
The nucleotide (p)ppGpp is almost ubiquitous in bacteria and is produced in response to a variety of environmental stimuli, allowing adaptation and survival. E. coli has primarily served as the model organism for studying (p)ppGpp metabolism and function, where it is synthesized by RelA and SpoT and directly interacts with RNA polymerase to change the global transcriptome. However, Gram-positive organisms appear to have different mechanisms of (p)ppGpp metabolism and action, which allow (p)ppGpp to respond to a variety of stresses without directly affecting RNA polymerase. For example, in Bacillus subtilis, (p)ppGpp directly regulates the activities of de novo and salvage GTP biosynthesis enzymes to both respond to starvation and to maintain GTP homeostasis. Here I will summarize our current understanding of the diverse mechanisms utilized by B. subtilis to produce and employ (p)ppGpp to modulate cellular physiology, ensure stress resistance and antibiotic tolerance.