# Synthesis and transport of outer membrane components across the Gram-negative cell envelope

> **NIH NIH R01** · UNIVERSITY OF GEORGIA · 2023 · $579,785

## Abstract

Abstract
The increasing rise in antibiotic resistance and the diminished discovery of new antimicrobials threatens global
healthcare. Of particular concern are Gram-negative pathogens, organisms with an additional outer membrane
(OM) that provides intrinsic resistance to multiple classes of antibiotics. Unlike the inner membrane (IM) that is
composed solely of glycerophospholipids (GPLs), the OM is asymmetrical with GPLs found in the inner leaflet
and lipopolysaccharide (LPS) localized to the outer leaflet. This unique membrane asymmetry affords
protection from large polar molecules, as well as lipophilic compounds, creating an impervious barrier. Since
the OM is essential, pathways required for its assembly are key targets for antimicrobial design. Currently,
there are no antibiotics that directly target OM biogenesis in clinical use. Thus, it remains critical to investigate
cell envelope biogenesis for future and current antimicrobial design.
Over the last few decades, we have expanded our understanding of OM assembly revealing new targets for
antimicrobial design. However, one major gap remained. How are GPLs transported from the IM to the OM
across the aqueous periplasm? Recently, we discovered that key members of the AsmA-like family (YhdP,
TamB, and YdbH) are critical for OM integrity and involved in GPL transport. We found that YhdP, TamB, and
YdbH are redundant in their role in OM lipid homeostasis; however, they are not equivalent. Notably, all three
proteins share homology and structural features with eukaryotic GPL transporters and are capable of spanning
the periplasm. The overall objective of this application is to investigate the molecular mechanisms required
for the assembly and maintenance of the Gram-negative OM. More specifically, we will characterize pathways
required to transport GPLs across the cell envelope using E. coli as the model system. In the current
application we will (i) characterize the major GPL transporters (YhdP, TamB, and YdbH), (ii) identify accessory
proteins required for GPL transbilayer movement, and (iii) determine how loss of these systems impact OM
lipid homeostasis and antibiotic resistance.

## Key facts

- **NIH application ID:** 10680968
- **Project number:** 1R01AI176776-01
- **Recipient organization:** UNIVERSITY OF GEORGIA
- **Principal Investigator:** Michael Stephen Trent
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2023
- **Award amount:** $579,785
- **Award type:** 1
- **Project period:** 2023-01-27 → 2027-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10680968

## Citation

> US National Institutes of Health, RePORTER application 10680968, Synthesis and transport of outer membrane components across the Gram-negative cell envelope (1R01AI176776-01). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10680968. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*