PROJECT SUMMARY
Bacteria are enveloped in sugary layers that maintain cell shape, protect against osmotic pressure, and resist
environmental hazards. In Gram-negative bacteria, the cell envelope surrounds the cytoplasm and includes a
cytoplasmic (inner) membrane, a thin peptidoglycan (PG) cell wall, and an outer membrane. The cell envelope
is essential and is therefore a prominent target for antibacterials and vaccines. However, bacteria continue to
develop new ways to evade these life-saving compounds. Thus, it is imperative that we understand the
mechanisms of cell envelope assembly, ultimately to design new modes of interference. One poorly understood
aspect of assembly revolves around the essential lipid carrier undecaprenyl phosphate (Und-P). Bacterial
surface glycans, including PG and other clinically important polysaccharides, are assembled on and transported
across the cytoplasmic membrane by Und-P. While decreasing the pool of Und-P induces cells to grow poorly
and die, little to no effort has been applied to understand what effects occur when the pool of Und-P increases.
Therefore, we will manipulate pathways that create Und-P to determine how maximizing the pool of Und-P affects
Und-P-dependent processes. Similarly, pathways compete for a common pool of Und-P, but no one knows how
this is done. Since such information is fundamental to disrupting the relationships among Und-P-utilizing
pathways, we will manipulate pathways that use Und-P. Another poorly understood aspect of Und-P metabolism
surrounds its utilization. Und-P inhibitors disrupt Und-P-dependent polymer formation, but how cells prioritize
pathways when Und-P becomes limiting is not known. To that end, we will characterize Und-P pathways
(including a potential new pathway) in Escherichia coli cells disrupted for Und-P metabolism. Finally, we will
continue to pursue results from a genetic screen in a mutant defective for Und-P recycling, which has uncovered
new and unexpected connections to Und-P metabolism that we propose to characterize in detail. In summary,
results from this study will enable us to understand, in greater detail, the mysteries surrounding Und-P utilization
and cell envelope assembly. At the same time, the tools and knowledge developed in the course of this work
promise to provide signal benefits for those working on the design of antimicrobial therapies.
