Mechanism and specificity of bacterial two-component signaling systems

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Biology, 2010.Includes bibliographical references (p. 57-60).Bacterial two component signaling (TCS) systems are the predominant means by which bacteria sense and respond to external signals. These systems represent a large family of paralogous proteins; often hundreds of the histidine kinase (HK) and response regulator (RR) pairs that make up a TCS system can be found in a single cell. How do these systems maintain faithful signal transmission and avoid cross-talk? To understand how specificity is determined, we examined co-evolving residues between HKs and RRs, and guided by this, aimed to rewire specificity of several activities of TCS systems. Previous work in the lab has successfully rewired specificity of histidine kinases for response regulators in the phosphotransfer reaction. By mutating different subsets of these co-evolving residues, we were able to rewire specificity of RRs in the phosphotransfer reaction, and partially rewire specificity of HKs and RRs in the phosphatase reaction. Additionally, we identified residues that may dictate specificity between two domains of the histidine kinase, and found that mutating them altered the rate of autophosphorylation. These analyses will allow rational rewiring of two component systems in vivo, and permit us to examine the fitness consequences of this altered specificity, providing insight into the evolutionary pressures on TCS systems.by Emma A. Lubin.S.M

Global characterization of the Pho regulon in Caulobacter crescentus

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Biology, 2014.Cataloged from PDF version of thesis.Includes bibliographical references.Bacteria must sense and respond to their environment in order to survive and proliferate. Adapting to phosphate-limited conditions is particularly critical, as phosphate is a central component of many important biomolecules. Most bacteria respond to phosphate limitation through a widely conserved pathway, composed of the phosphate transport Pst system, and downstream signal transduction pathway, PhoR-PhoB, termed the Pho system. In this thesis, I use the model organism Caulobacter crescentus to characterize the response to phosphate limitation. I use ChIP-Seq on the transcriptional regulator PhoB to globally map the Pho regulon in Caulobacter in both phosphate-starved and -replete conditions. I find that the regulatory regions of over 50 genes are bound by PhoB following phosphate limitation, and I identify a consensus PhoB binding motif in Caulobacter. I then examine the function of PhoU, which is a putative negative regulator of the Pho regulon in Caulobacter and many other bacteria. I use morphological and microarray data to demonstrate that PhoU is not a negative regulator of the Pho regulon, and that it instead acts outside the PhoR-PhoB pathway. I find that the function of PhoU is tightly linked to cellular phosphate metabolism. This work offers insight into how Caulobacter responds to nutrient stress, as well as a better understanding of the connectivity and output of the phosphate limitation response pathway.by Emma A. Lubin.Ph. D

Snowmass 2021 CMB-S4 White Paper

This Snowmass 2021 White Paper describes the Cosmic Microwave Background Stage 4 project CMB-S4, which is designed to cross critical thresholds in our understanding of the origin and evolution of the Universe, from the highest energies at the dawn of time through the growth of structure to the present day. We provide an overview of the science case, the technical design, and project plan

Snowmass 2021 CMB-S4 White Paper

This Snowmass 2021 White Paper describes the Cosmic Microwave Background Stage 4 project CMB-S4, which is designed to cross critical thresholds in our understanding of the origin and evolution of the Universe, from the highest energies at the dawn of time through the growth of structure to the present day. We provide an overview of the science case, the technical design, and project plan

Snowmass 2021 CMB-S4 White Paper

This Snowmass 2021 White Paper describes the Cosmic Microwave Background Stage 4 project CMB-S4, which is designed to cross critical thresholds in our understanding of the origin and evolution of the Universe, from the highest energies at the dawn of time through the growth of structure to the present day. We provide an overview of the science case, the technical design, and project plan

Snowmass 2021 CMB-S4 White Paper

This Snowmass 2021 White Paper describes the Cosmic Microwave Background Stage 4 project CMB-S4, which is designed to cross critical thresholds in our understanding of the origin and evolution of the Universe, from the highest energies at the dawn of time through the growth of structure to the present day. We provide an overview of the science case, the technical design, and project plan

Snowmass 2021 CMB-S4 White Paper

This Snowmass 2021 White Paper describes the Cosmic Microwave Background Stage 4 project CMB-S4, which is designed to cross critical thresholds in our understanding of the origin and evolution of the Universe, from the highest energies at the dawn of time through the growth of structure to the present day. We provide an overview of the science case, the technical design, and project plan

Snowmass 2021 CMB-S4 White Paper

This Snowmass 2021 White Paper describes the Cosmic Microwave Background Stage 4 project CMB-S4, which is designed to cross critical thresholds in our understanding of the origin and evolution of the Universe, from the highest energies at the dawn of time through the growth of structure to the present day. We provide an overview of the science case, the technical design, and project plan

Snowmass 2021 CMB-S4 White Paper

This Snowmass 2021 White Paper describes the Cosmic Microwave Background Stage 4 project CMB-S4, which is designed to cross critical thresholds in our understanding of the origin and evolution of the Universe, from the highest energies at the dawn of time through the growth of structure to the present day. We provide an overview of the science case, the technical design, and project plan