In vitro and in silico investigations of changes in bacterial cell membrane dynamics due to polyunsaturated fatty acid (PUFA) modifications - Project Summary/Abstract
Bacterial responses to fatty acids include, but are not limited to, degradation for metabolic gain, modification of
membrane lipids, alteration of protein function and regulation of gene expression. Vibrio species exhibit
significant diversity with regard to the machinery known to participate in the uptake and incorporation of fatty
acids into their membranes. Both aquatic and host niches occupied by Vibrio are rife with various free fatty acids
and fatty acid-containing lipids. The roles of fatty acids in the survival and pathogenesis of bacteria have begun
to emerge and are expected to expand significantly. Compared to the import mechanisms of minerals (e.g., iron)
and sugars (e.g., lactose), the process and significance of scavenging and handling fatty acids is punctuated
with gaps in knowledge.
Gaining a better understanding of how microbes harness environment-specific resources will shed light
on several themes of pathogenesis, such as environmental persistence, transmission to humans, and course of
disease. The varied abilities of bacteria to recognize, uptake and utilize lipid molecules from their environment
certainly represents a worthwhile research endeavor. It is hypothesized that Vibrio cholerae undergoes
significant structural modifications to its membrane phospholipids depending on the exogenously available
polyunsaturated fatty acids (PUFAs), and that these alterations affect membrane permeability sufficient to
change the susceptibility to membrane active antimicrobials. The proposed project seeks to advance a specific
mission of the NIGMS: to increase our understanding of biological processes and lay the foundation for advances
in disease diagnosis, treatment, and prevention. Accordingly, the research aims are to i) interrogate the nature
and degree of polyunsaturated fatty acid (PUFA) incorporation into membrane phospholipids and ii) examine the
altered membrane dynamics and antibiotic susceptibility conferred by exogenously acquired PUFAs.
Bioanalytical methodologies (thin-layer chromatography and UPLC/MS) will quantify and structurally
characterize exogenous PUFA-mediated phospholipid modifications. Interrogation of membrane permeability
will be performed in vitro using established dye-based assays and in silico with atomistic modeling and simulation
analyses. Collectively, the data will lay the foundation for deciphering a versatile pathway in Gram-negative
bacteria by defining PUFA assimilation capability and its impact on membrane permeability, a critical cellular
attribute that must be characterized in the interest of developing strategies to combat infection.
The results of these studies should contribute to our current understanding of how and why bacteria have
evolved to utilize a variety of exogenous lipid molecules, thus providing insight into their survival both outside
and within the host, as well as unlocking pathways vulnerable to antimicrobial attack.
