Restricted Research - Award List, Note/Discussion Page
Fiscal Year: 2023
337 The University of Texas Rio Grande Valley (142225)
Principal Investigator: Touhami,Ahmed
Total Amount of Contract, Award, or Gift (Annual before 2011): $ 44,240
Exceeds $250,000 (Is it flagged?): No
Start and End Dates: 4/1/22 - 3/31/25
Restricted Research: YES
Academic Discipline: Physics and Astronomy
Department, Center, School, or Institute: Physics and Astronomy
Title of Contract, Award, or Gift: A predictive framework for understanding bacterial mechanosensing
Name of Granting or Contracting Agency/Entity:
University of Texas at Austin
CFDA Link: NSF
47.041
Program Title:
Engineering
CFDA Linked: Engineering Grants
Note:
SAMs 1.1.1--Most bacteria have a cell wall that maintains cell shape and protects against osmotic lysis. The strength and rigidity conferred by the cell wall results from a layer of peptidoglycan, which is a covalent macromolecular structure of stiff glycan chains that are cross-linked by flexible peptide bridges. Unique to the bacterial world, this large polymer network is also the principal target of many antibiotics and one of the main microbial products recognized by the immune system. Consequently, great efforts have been invested in the past decade to determine its architecture and biosynthesis. While chemical composition and structure of fragments have been established, and several enzymes involved in peptidoglycan assembly have been isolated, the three-dimensional organization of this biopolymer is still debated (orientation of the glycan strands parallel or perpendicular to the cell membrane has been proposed), and its growth mechanism remains an area of active research. The large size, structural heterogeneity, and flexibility of the peptidoglycan sacculi preclude crystal formation and hence determination of the crystal structure. Furthermore, the glycan strands and peptides cannot be visualized by conventional electron microscopy because their dimensions are of the same scale as the inevitable staining and fixation artifacts. Thus, current models of the peptidoglycan architecture are based on very limited biochemical data and underlying assumptions about glycan length distribution, glycan conformation and structural regularity that deserve careful consideration. The research aims of this project are: (1) to determine the length distribution of glycan strands over the bacterial life cycle, and (2) to determine their conformation, mechanics, and dynamics at the level of single glycan strand. A combination of Real-time AFM imaging, force spectroscopy, enzymatic degradation, and local mechanical forces will be used to investigate purified isolated sacculi from gram-negative and gram-positive bacteria. The knowledge of the exact glycan length, elasticity, and conformation are prerequisites for unraveling the unknown molecular architecture of this fascinating macromolecule. The long-term goal of this research project is to develop a molecular understanding of how the peptidoglycan stress-bearing dynamic three-dimensional structure is related to the shape determination and force generation in bacteria. Data from this proposal may provide the foundation for novel therapeutic interventions for bacterial infections.
Discussion: No discussion notes