# Contribution of extracellular enzymes to Staphylococcus aureus biofilm development

> **NIH NIH P01** · UNIVERSITY OF NEBRASKA MEDICAL CENTER · 2021 · $465,368

## Abstract

PROJECT SUMMARY
Staphylococcus aureus is one of the most problematic bacterial pathogens in our healthcare settings. S. aureus
can survive and persist in the host by developing into an encased community of cells called a biofilm, and
numerous studies have demonstrated that biofilms are resistant to host immune defenses and chemotherapies.
Our central PPG hypothesis is that S. aureus biofilm development creates unique metabolic niches that promote
an immune suppressive environment. In this proposal (Project 3), we are focusing on the contribution of S.
aureus extracellular enzymes to biofilm growth and maturation, persistence in the host, and ultimately
dissemination to a new site. Of the many enzymes that S. aureus secretes, we will prioritize hyaluronidase (HysA)
and nuclease (Nuc1), as they have commonalities in biofilm-host interaction phenotypes and regulatory
schemes. We recently demonstrated that hyaluronan accumulates in an S. aureus biofilm infection and that
HysA can degrade this host glycosaminoglycan to disaccharides (HA-DS). Our preliminary studies indicate that
HA-DS can serve as a carbon source through an unknown catabolic pathway, and this disaccharide has
additional anti-inflammatory properties that could be contributing to the persistent nature of S. aureus biofilm
infections. In Specific Aim 1, we will determine the role and regulation of hyaluronan metabolism in S. aureus
biofilm maturation. We will characterize the HA-DS catabolic pathway using genetic analysis and labeling studies
in collaboration with the Metabolomics Core. We will also test catabolic pathway knockouts in biofilm maturation
and foreign-body infections, and investigate the contribution of CodY and CcpA to regulation of hyaluronan
catabolism. Additionally, S. aureus will be grown on HA-DS and RNAseq performed to identify global
transcriptomic changes. In Specific Aim 2, we will investigate how S. aureus enzymatic degradation of host
polymers impacts the biofilm anti-inflammatory state. In collaboration with Dr. Tammy Kielian (PPG Project 4),
we will assess the effect of HA-DS, as well as Nuc1 and HysA enzymes and their regulators, on immune cell
function. We will also determine the impact of HA-DS and HysA inhibitors on biofilm infection, and test whether
HA-DS is a biomarker for S. aureus in human synovial fluid from patients with prosthetic joint infection (PJI). In
Specific Aim 3, we will examine S. aureus exo-enzyme regulation and function in biofilm dispersal. We
hypothesize that CodY controls dissemination from S. aureus biofilms in an enzyme and nutrient dependent
manner. We will investigate the contribution of Nuc1 and HysA, along with CodY and SaeRS regulators, to biofilm
dispersal in vitro and during foreign body infection. We will also examine the impact of nutritional status on CodY
activity during biofilm formation and dispersal in collaboration with Dr. Ken Bayles (PPG Project 1) and the
Bioimaging Core. Finally, we will determine the role of aur...

## Key facts

- **NIH application ID:** 10198699
- **Project number:** 5P01AI083211-13
- **Recipient organization:** UNIVERSITY OF NEBRASKA MEDICAL CENTER
- **Principal Investigator:** Tammy L Kielian
- **Activity code:** P01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $465,368
- **Award type:** 5
- **Project period:** 2009-07-01 → 2024-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10198699

## Citation

> US National Institutes of Health, RePORTER application 10198699, Contribution of extracellular enzymes to Staphylococcus aureus biofilm development (5P01AI083211-13). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10198699. Licensed CC0.

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