Journal article
Signal Peptidase-Mediated Cleavage of the Anti-σ Factor RsiP at Site 1 Controls σ P Activation and β-Lactam Resistance in Bacillus thuringiensis
mBio, Vol.13(1), pp.e0370721-e0370721
02/22/2022
DOI: 10.1128/mbio.03707-21
PMCID: PMC8844934
PMID: 35164554
Abstract
β-Lactam antibiotics are important for the treatment of many bacterial infections. However, resistance mechanisms have become increasingly more prevalent.
ABSTRACT
In
Bacillus thuringiensis
, β-lactam antibiotic resistance is controlled by the extracytoplasmic function (ECF) σ factor σ
P
. σ
P
activity is inhibited by the anti-σ factor RsiP. In the presence of β-lactam antibiotics, RsiP is degraded and σ
P
is activated. Previous work found that RsiP degradation requires cleavage of RsiP at site 1 by an unknown protease, followed by cleavage at site 2 by the site 2 protease RasP. The penicillin-binding protein PbpP acts as a sensor for β-lactams. PbpP initiates σ
P
activation and is required for site 1 cleavage of RsiP but is not the site 1 protease. Here, we describe the identification of a signal peptidase, SipP, which cleaves RsiP at a site 1 signal peptidase cleavage site and is required for σ
P
activation. Finally, many
B. anthracis
strains are sensitive to β-lactams yet encode the σ
P
-RsiP signal transduction system. We identified a naturally occurring mutation in the signal peptidase cleavage site of
B. anthracis
RsiP that renders it resistant to SipP cleavage. We find that
B. anthracis
RsiP is not degraded in the presence of β-lactams. Altering the
B. anthracis
RsiP site 1 cleavage site by a single residue to resemble
B. thuringiensis
RsiP results in β-lactam-dependent degradation of RsiP. We show that mutation of the
B. thuringiensis
RsiP cleavage site to resemble the sequence of
B. anthracis
RsiP blocks degradation by SipP. The change in the cleavage site likely explains many reasons why
B. anthracis
strains are sensitive to β-lactams.
IMPORTANCE
β-Lactam antibiotics are important for the treatment of many bacterial infections. However, resistance mechanisms have become increasingly more prevalent. Understanding how β-lactam resistance is conferred and how bacteria control expression of β-lactam resistance is important for informing the future treatment of bacterial infections. σ
P
is an alternative σ factor that controls the transcription of genes that confer β-lactam resistance in
Bacillus thuringiensis
,
Bacillus cereus
, and
Bacillus anthracis
. Here, we identify a signal peptidase as the protease required for initiating activation of σ
P
by the degradation of the anti-σ factor RsiP. The discovery that the signal peptidase SipP is required for σ
P
activation highlights an increasing role for signal peptidases in signal transduction, as well as in antibiotic resistance.
Details
- Title: Subtitle
- Signal Peptidase-Mediated Cleavage of the Anti-σ Factor RsiP at Site 1 Controls σ P Activation and β-Lactam Resistance in Bacillus thuringiensis
- Creators
- Kelsie M. Nauta - University of IowaTheresa D. Ho - University of IowaCraig D. Ellermeier - University of Iowa
- Contributors
- Eduardo A. Groisman (Editor)
- Resource Type
- Journal article
- Publication Details
- mBio, Vol.13(1), pp.e0370721-e0370721
- DOI
- 10.1128/mbio.03707-21
- PMID
- 35164554
- PMCID
- PMC8844934
- NLM abbreviation
- mBio
- ISSN
- 2150-7511
- eISSN
- 2150-7511
- Grant note
- DOI: 10.13039/100000060, name: HHS | NIH | National Institute of Allergy and Infectious Diseases, award: R21AI146769
- Language
- English
- Date published
- 02/22/2022
- Academic Unit
- Microbiology and Immunology
- Record Identifier
- 9984297329202771
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