Local and global regulation of bacterial growth

Johns Hopkins University, Baltimore MD

Investigators

Linked publications, trials & patents

Abstract

To impact human health, bacteria must reproduce through successive rounds of growth and division. Moreover, bacterial cells must adapt their growth to changing environmental conditions, including changes in nutrient availability or the presence of antibiotics, to ensure survival. In our proposed work, we focus on two questions relevant to bacterial growth and adaptation. In the first, we ask how do bacterial cells locally regulate growth during cell division (cytokinesis)? To address this question, we will build on our recent work demonstrating that the conserved polymerizing GTPase FtsZ is a dynamic regulator of cell wall synthesis and remodeling during cell division. This idea represents a paradigm shift in defining FtsZ as an active regulator, rather than passive scaffold, for cell wall metabolism. We will leverage our expertise in bacterial genetics, imaging, biochemistry, and in vitro reconstitution to map the players and mechanisms in two signaling pathways from FtsZ to cell wall metabolism we identified in our model organism, Caulobacter crescentus. Given the urgent need for new antibiotics and proven efficacy of the cell wall as an antibacterial target, a complete understanding of the mechanisms and regulation of cell wall metabolism is a critical goal. In our second question, we ask how do bacteria adapt to changing nutrient availability and other stresses? We recently described the role of a conserved transcriptional regulator called CdnL in regulating metabolism, specifically in upregulating biosynthetic pathways, in Caulobacter. In addition, we have observed that CdnL is cleared from the cell during nutrient limitation in a manner dependent on the signaling alarmone ppGpp, suggesting a mechanism by which cells may downregulate proliferative processes when nutrients are scarce. We will use a combination of genetic, genomic, and biochemical approaches to determine the contributions of CdnL inactivation and ppGpp to reprogramming transcription to ensure bacterial survival during nutrient limitation and other stresses. As both CdnL and ppGpp are implicated in adaptation to a variety of stresses in diverse bacteria, this work will inform our understanding stress and antibiotic resistance mechanisms in important bacterial pathogens. The project summary is a succinct and accurate description of the proposed work and should be able to stand on its own (separate from the application). This section should be informative to other persons working in the same or related fields and understandable to a scientifically literate reader. Avoid both descriptions of past accomplishments and the use of the first person. Please be concise. Format: This section is limited to 30 lines of text, and must follow the required font and margin specifications. A summary which exceeds this length will be flagged as an error by the Agency upon submission. You will need to take corrective action before the application can be accepted. Attach this information as a PDF file. See the Format Attachments page. Content: State the application's broad, long-term objectives and specific aims, making reference to the health relatedness of the project (i.e., relevance to the mission of the agency). Describe the research design and methods for achieving the stated goals. Be sure that the project summary reflects the key focus of the proposed project so that the application can be appropriately categorized. Do not include proprietary, confidential information or trade secrets in the project summary. If the application is funded, the project summary will be entered into an NIH database and made available on the NIH Research Portfolio Online Reporting Tool (RePORT) and will become public information. Note that the "Project Summary/Abstract" attachment is not same as the "Research Strategy" attachment.