Project Grant R01GM149611

MECHANISMS OF CELL-SIZE CONTROL IN GRAM-NEGATIVE BACTERIA - PROJECT SUMMARY TO GROW AND SURVIVE, BACTERIA RELY ON A MULTITUDE OF PHYSIOLOGICAL PROCESSES OCCURRING ALONG AND ACROSS THE CELL ENVELOPE, INCLUDING NUTRIENT UPTAKE, RESPIRATION, AND THE SECRETION OF WASTE PRODUCTS. THESE PROCESSES ARE SUSTAINED BY A DENSE ARRANGEMENT OF PROTEINS LOCATED WITHIN AND ALONG THE CELL ENVELOPE. TO BETTER PREDICT BACTERIAL GROWTH BEHAVIOR IN DIFFERENT ENVIRONMENTS IT IS THUS ESSENTIAL TO BETTER UNDERSTAND HOW BACTERIAL CELLS CONTROL THEIR ENVELOPE PROTEOME DEPENDING ON THEIR CELL-PHYSIOLOGICAL STATE AND THE SPECIFIC CHARACTERISTICS OF THE ENVIRONMENT THEY ENCOUNTER. THIS RESEARCH INTEGRATES EXPERIMENTS AND MATHEMATICAL MODELING TO PROMOTE SUCH A SYSTEMS-LEVEL UNDERSTANDING OF THE CELL ENVELOPE IN ROD-SHAPED GRAM-NEGATIVE BACTERIA. ENVELOPE PROTEINS IN GRAM-NEGATIVE BACTERIA ARE DISTRIBUTED ACROSS TWO MEMBRANES AND THE PERIPLASMIC SPACE ENCLOSED BY THESE MEMBRANES. AS THE DIMENSIONS OF THESE ENVELOPE LAYERS ARE INHERENTLY LINKED TO THE SIZE OF THE CELL, THIS STUDY TIGHTLY INTEGRATES CELL-SIZE CONTROL TO INVESTIGATE HOW ENVELOPE PROTEIN MASSES AND ENVELOPE SIZE ARE REGULATED BY THE CELL. EXPERIMENTALLY, MICROSCOPY, GENETIC ENGINEERING, AND A NOVEL BIOCHEMICAL ASSAY ARE COMBINED TO QUANTIFY CHANGES IN CELL SIZE AND THE ENVELOPE PROTEOME ACROSS BACTERIAL SPECIES AND FOR A BROAD RANGE OF PHYSIOLOGICALLY DISTINCT GROWTH CONDITIONS. MATHEMATICALLY, BAYESIAN INFERENCE AND RESOURCE ALLOCATION MODELS ARE INTEGRATED TO DISMANTLE THE INTERDEPENDENCE OF MEASURED QUANTITIES AND SPECIFICALLY PROBE THE ROLE OF TWO HYPOTHESIZED CONSTRAINTS OF ENVELOPE COMPOSITION AND CELL SIZE CONTROL: MACROMOLECULAR DENSITY AND ASPECT-RATIO MAINTENANCE. THE THREE SPECIFIC AIMS ARE: (I) REVEALING THE FUNDAMENTAL GROWTH LAWS OF ENVELOPE COMPOSITION AND CELL SIZE IN DIFFERENT GRAM-NEGATIVE SPECIES. (II) ESTABLISHING A DYNAMICAL RESOURCE ALLOCATION MODEL TO PREDICT ADJUSTMENT OF CELL SIZE AND ENVELOPE COMPOSITION OVER THE CELL CYCLE. (III) PROBING THE MOLECULAR REGULATION OF ENVELOPE-DEPENDENT ASPECT-RATIO CONTROL. MAJOR PATHOGENIC BACTERIA BELONG TO THE GROUP OF ROD-SHAPED GRAM-NEGATIVES CONSIDERED IN THIS STUDY, INCLUDING FIVE OF THE SEVEN ESKAPEE PATHOGENS KNOWN FOR THEIR AGGRESSIVE ACQUISITION OF MULTIPLE ANTIBIOTICS RESISTANCE. AS SUCH, THIS SYSTEMATIC STUDY OF ENVELOPE AND SIZE CONTROL BUILDS AN IMPORTANT PHYSIOLOGICAL FOUNDATION FOR THE TARGETED DEVELOPMENT OF NOVEL PREVENTION AND TREATMENT STRATEGIES AGAINST AN INCREASING GLOBAL HEALTH THREAT.