# Function and maintenance of molecules at the surface of Acinetobacter baumannii

> **NIH NIH F32** · UNIVERSITY OF GEORGIA · 2020 · $64,926

## Abstract

Abstract
Bacteria have evolved different cell envelope compositions that provide them specific advantages in their natural
environments or as human pathogens. Two major types of didermic bacteria, containing cell envelopes with two
lipid membranes, have been discovered that differ by the composition of the surface of their outer membranes
(OM). Gram-negative bacteria (e.g. Escherichia coli) contain a surface layer of lipopolysaccharides (LPS) that
produces a stringent permeability barrier at the OM and make them resistant to many antibiotics. In addition,
LPS biogenesis is essential in most Gram-negative bacteria, although the reason why has remained elusive.
Other diderms (e.g. many spirochetes) have glycerophospholipids (GPLs) and lipoproteins at the surface of the
OM. Surface lipoproteins have many critical roles in pathogenesis, nutrient acquisition, and signaling. However,
how lipoproteins reach the surface of the OM has remained unknown for most bacteria in which they are found.
The high-priority Gram-negative pathogen, Acinetobacter baumannii, is remarkably able to survive with an OM
containing either LPS or GPLs and lipoproteins at the surface. A. baumannii naturally produces an LPS-
containing OM. However, this bacterium is able to survive with complete inactivation of LPS biogenesis. Loss of
LPS at the cell surface is accompanied by up-regulation of surface-exposed lipoproteins. The primary objective
of this application is to investigate the function and assembly of molecules on the surface of the cell, LPS and
lipoproteins, using LPS-containing and LPS-deficient A. baumannii. In Aim 1, we will take both a directed
approach, to investigate the role of surface lipoproteins during LPS-deficiency, and a non-biased approach, to
identify additional genetic requirements for LPS-deficient A. baumannii. In Aim 2, we will characterize how
lipoproteins reach the surface of the OM in A. baumannii. We will target genes implicated in lipoprotein transport
in other bacteria, and perform an unbiased screen to identify genes involved in surface localization. The
remarkable ability of A. baumannii to grow with two different OM compositions, provides a unique opportunity to
explore the advantages each provides to bacterial cells. This application is built on a strong scientific premise
addressing major gaps in our understanding of the pathogen, A. baumannii, that will have broad implications
towards cell envelope biogenesis and possible treatment of both Gram-negative and other didermic bacteria.
The application will be completed by the principal investigator in the lab of Dr. M. Stephen Trent (sponsor) at the
University of Georgia. Both of which are committed to providing trainees with research (e.g. core facilities in
genomics, microscopy, etc.) and career development resources (e.g. training in grantsmanship, teaching,
mentoring, etc.). Completion of the fellowship will provide training in new techniques (e.g. lipidomics), new fields
of research (e.g....

## Key facts

- **NIH application ID:** 9990948
- **Project number:** 1F32GM137554-01
- **Recipient organization:** UNIVERSITY OF GEORGIA
- **Principal Investigator:** Brent Simpson
- **Activity code:** F32 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $64,926
- **Award type:** 1
- **Project period:** 2020-09-01 → 2022-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9990948

## Citation

> US National Institutes of Health, RePORTER application 9990948, Function and maintenance of molecules at the surface of Acinetobacter baumannii (1F32GM137554-01). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9990948. Licensed CC0.

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