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Principal Investigator: Mario Feldman
Organization: WASHINGTON UNIVERSITY
Fiscal Year: 2024
Award: $681,308
Funding agency: National Institute of Allergy and Infectious Diseases
PROJECT SUMMARY/ABSTRACT
Multidrug resistant (MDR) infections caused by the bacterial pathogen Acinetobacter baumannii are increasing
at alarming rates. Currently, over 60 % of global A. baumannii clinical isolates are MDR, leading the Centers for
Disease Control and Prevention and the World Health Organization to categorize it as a top priority for the
research and development of new antimicrobial therapies. In addition to accumulating resistance mechanisms,
A. baumannii strains develop tolerance to antibiotics, which can frequently lead to poor therapeutic outcomes
even with antibiotic susceptible strains. However, the mechanisms used by A. baumannii to adapt to and tolerate
hostile conditions remain largely unknown. We found that A. baumannii employs a novel stress response
pathway in which phenylacetic acid (PAA), a metabolite derived from phenylalanine catabolism, acts as a
signaling molecule. We established that, in the presence of sub-inhibitory concentrations of different antibiotics,
such as trimethoprim/sulfamethoxazole, A. baumannii dramatically increases the transcription of the paa operon
which encodes enzymes required to degrade PAA. Conversely, other conditions, like hydrogen peroxide
treatment, lead to a repression of the paa operon. The regulation of the paa operon triggers a physiological
adaptive response that includes the modulation of pili biosynthesis and biofilm formation. Importantly, we found
that artificial augmentation of PAA levels, through the addition of commercially available PAA-derivatives or
mutations in PAA degradative genes, disrupts this response Furthermore, mutating initial steps of PAA
degradation leads to increased sensitivity to antibiotics and oxidative stress in multiple strains. Here we propose
to use our expertise in A. baumannii genetics and pathogenesis to investigate the PAA-mediated stress response
in Acinetobacter and determine its importance in virulence. We will determine the breadth of PAA signaling using
reporter assays, and we will explore PAA-mediated changes in cell physiology by profiling gene expression
under different stress conditions. Further, we will characterize the PAA-dependent mechanisms of cell signaling
under stress by measuring cellular levels of PAA and determining the role of important regulatory proteins in this
cascade. Finally, we will test the virulence of strains unable to regulate PAA levels in the catheter-associated
urinary tract infection and lung infection murine models. Our work will establish the role of PAA as a key
regulatory molecule in A. baumannii, determine the biological processes regulated by PAA, and uncover the
mechanisms by which PAA triggers adaptations to promote survival under stress. Understanding the
fundamental aspects of the PAA stress response will provide a foundation to future clinical studies.
Terms: <A baumanni><A baumannii><A. baumanni><A. baumannii><A.baumannii><Acinetobacter><Acinetobacter Infections><Acinetobacter baumanni><Acinetobacter baumannii><Acute><Adherence><Affect><Anabolism><Antibiotic Agents><Antibiotic Drugs><Antibiotic Therapy><Antibiotic Treatment><Antibiotic susceptibility><Antibiotics><Assay><Auxins><Bioassay><Biological Assay><Biological Function><Biological Process><Catabolism><Categories><Cell Body><Cell Communication and Signaling><Cell Function><Cell Physiology><Cell Process><Cell Signaling><Cells><Cellular Function><Cellular Physiology><Cellular Process><Centers for Disease Control><Centers for Disease Control and Prevention><Centers for Disease Control and Prevention (U.S.)><Clinical><Clinical Research><Clinical Study><Collaborations><Cytoplasm><Development and Research><Disease><Disorder><Environment><Enzyme Gene><Enzymes><Epithelial Cells><Exposure to><Extracellular Matrix Proteins><Fe element><Foundations><Future><Gene Down-Regulation><Gene Expression><Gene Transcription><Genes><Genetic><Genetic Alteration><Genetic Change><Genetic Transcription><Genetic defect><Genetics-Mutagenesis><H2O2><HPLC><High Performance Liquid Chromatography><High Pressure Liquid Chromatography><High Speed Liquid Chromatography><Hospitals><Hydrogen Peroxide><Hydroperoxide><Hypoxia><Hypoxic><Infection><Intracellular Communication and Signaling><Intracellular Second Messenger><Iron><Lead><Life><Lung infections><MDR Acinetobacter><Measures><Mediating><Mice><Mice Mammals><Microbial Biofilms><Mimae Infections><Miscellaneous Antibiotic><Modeling><Molecular><Multi-Drug Resistance><Multi-drug resistant Acinetobacter><Multidrug Resistance><Multidrug-resistant Acinetobacter><Multiple Drug Resistance><Multiple Drug Resistant><Murine><Mus><Mutagenesis><Mutagenesis Molecular Biology><Mutate><Mutation><Operon><Osmosis><Oxidative Stress><Oxygen Deficiency><Pathogenesis><Pathway interactions><Pb element><Phagocytes><Phagocytic Cell><Phenotype><Phenylalanine><Physiologic><Physiological><Pilum><Plants><Process><Production><Proloprim><Property><R & D><R&D><RNA Expression><Regulation><Regulatory Protein><Reporter><Repression><Research Priority><Resistance to Multi-drug><Resistance to Multidrug><Resistance to Multiple Drug><Resistant to Multiple Drug><Resistant to multi-drug><Resistant to multidrug><Role><SMX><Second Messenger Systems><Second Messengers><Signal Pathway><Signal Transduction><Signal Transduction Systems><Signaling><Signaling Molecule><Stress><Subcellular Process><Sulfamethoxazole><Sulfamethylisoxazole><Sulfisomezole><System><Testing><Therapeutic><Transcription><Transcription Repression><Transcriptional Repression><Trimethoprim><Trimpex><United States Centers for Disease Control><United States Centers for Disease Control and Prevention><Urinary tract infection><Urinary tract infectious disease><Virulence><Work><World Health Organization><amebocyte><anti-microbial><antibiotic tolerance><antimicrobial><bacteria pathogen><bacterial disease treatment><bacterial infectious disease treatment><bacterial pathogen><biofilm><biological adaptation to stress><biological signal transduction><biosynthesis><catheter associated UTI><catheter associated urinary tract infection><clinical relevance><clinically relevant><combat><gene repression><genetic regulatory protein><genome mutation><heavy metal Pb><heavy metal lead><mouse model><multi-drug resistant><multidrug resistant><murine model><mutant><new therapeutic approach><new therapeutic intervention><new therapeutic strategies><new therapy approaches><new treatment approach><new treatment strategy><novel><novel therapeutic approach><novel therapeutic intervention><novel therapeutic strategies><novel therapy approach><pathogen><pathogenic bacteria><pathway><phenylacetic acid><pilus><pressure><prevent><preventing><pulmonary infections><reaction; crisis><regulatory gene product><research and development><resistance mechanism><resistant mechanism><response><signal transduction second messengers><social role><stress response><stress tolerance><stress; reaction><stressor><therapeutic outcome><therapy outcome><tolerance to antibiotics><tolerate antibiotics><transcriptomics><urinary infection><urinary tract catheter infection>