# BETA LACTAMASE MUTATIONS IN ANTIBIOTIC RESISTANCE

> **NIH NIH R01** · BAYLOR COLLEGE OF MEDICINE · 2024 · $479,544

## Abstract

Project Summary/Abstract
b-lactam antibiotics have a broad spectrum of anti-bacterial activity including important
Gram-positive and negative pathogens. b-lactams are the most widely used antibiotics and include
penicillins, cephalosporins and carbapenems. Bacterial resistance to these drugs, however, has
been steadily increasing, significantly reducing treatment options. The most common mechanism of
resistance is b-lactamase-catalyzed hydrolysis, which renders the antibiotics ineffective.
Carbapenems are used as antibiotics of last resort. The increasing use of these drugs, however, has
led to the emergence of carbapenemase enzymes. This group includes the KPC-2 b-lactamase that
effectively hydrolyzes nearly all b-lactam antibiotics and has spread globally to multiple species of
Enterobacteriaciae. K. pneumoniae strains producing KPC are a particular concern, as the mortality
rate for infections from such strains is 30-40%. The design of new antibiotics that escape hydrolysis
by KPC enzymes is a challenge. To achieve this, it is necessary to understand the catalytic
mechanism and basis for substrate specificity of the enzyme and how this relates to inhibitor design.
This, in turn, requires an understanding of the affinity of binding of the antibiotic/inhibitor as well as
the rates of the chemical steps. Further, it is necessary to understand how the structure and
dynamics of the enzyme influence drug binding and hydrolysis. Finally, for future antibiotic design, it
is important to understand how changes in antibiotic structure impact binding affinity and the rates of
chemical steps. We propose to achieve these goals with KPC-2 and variants of the enzyme that have
an extended substrate profile or provide resistance to the antibiotic/inhibitor combination
ceftazidime/avibactam. While there has been extensive characterization of b-lactamase structure
and steady-state enzyme kinetics, there is a large gap in understanding the rates of individual steps
of b-lactamase-catalyzed hydrolysis of b-lactam antibiotics. We will address this gap by determining
the chemical and structural basis of KPC-2 catalysis with a combination of pre-steady state kinetic,
X-ray crystallographic, and molecular dynamics simulation approaches. Aim 1 will provide a
mechanistic and structural basis for the hydrolysis of b-lactam antibiotics by the KPC-2 enzyme. The
studies in Aim 2 will characterize the kinetic and structural basis of increased hydrolysis of the
extended-spectrum cephalosporin, ceftazidime, by drug-resistant KPC variants. Finally, Aim 3 will
determine the structural and mechanistic basis of action of KPC-variant enzymes that are resistant to
the ceftazidime/avibactam inhibitor combination. Our multidisciplinary approach is expected to
answer these questions and lead to new concepts and tools to address the problem of
antibiotic/inhibitor resistance.

## Key facts

- **NIH application ID:** 10749925
- **Project number:** 5R01AI032956-32
- **Recipient organization:** BAYLOR COLLEGE OF MEDICINE
- **Principal Investigator:** Timothy Palzkill
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $479,544
- **Award type:** 5
- **Project period:** 1992-07-01 → 2026-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10749925

## Citation

> US National Institutes of Health, RePORTER application 10749925, BETA LACTAMASE MUTATIONS IN ANTIBIOTIC RESISTANCE (5R01AI032956-32). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10749925. Licensed CC0.

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