Journal article
Genome Sequences of Two Pseudomonas aeruginosa Isolates with Defects in Type III Secretion System Gene Expression from a Chronic Ankle Wound Infection
Microbiology spectrum, Vol.9(1), pp.e0034021-6
09/03/2021
DOI: 10.1128/Spectrum.00340-21
PMCID: PMC8552725
PMID: 34259549
Abstract
Effector proteins translocated into host cells by the Pseudomonas aeruginosa type III secretion system (T3SS) are critical for phagocytic avoidance and systemic spread of the microorganism. The T3SS genes are present in virtually all P. aeruginosa strains. When examined in environmental isolates and clinical specimens, expression of the T3SS genes is the rule. Isolates from the airways of cystic fibrosis (CF) patients are one exception, and these isolates usually carry mutations that disable T3SS gene expression. In this study, we describe two P. aeruginosa isolates, one pigmented brown and one green, from a keratitis-ichthyosis-deafness (KID) syndrome patient with a chronic cutaneous ankle wound. Similar to most isolates from CF, both of the KID isolates were defective for T3SS gene expression. Providing the primary activator of T3SS transcription (
) in
restored T3SS function. Since the
sequences were identical to that of a reference strain with active T3SS gene expression, we examined the cAMP-Vfr system, a critical regulator of T3SS gene expression. Vfr is a cAMP-dependent transcription factor that activates
expression. Whereas T3SS activity was corrected in the brown isolate by restoring cAMP synthesis, the same was not observed for the green isolate. These findings suggest that distinct mechanisms resulted in loss of T3SS gene expression in the KID isolates. The mutations responsible for the T3SS defects were not clearly evident by comparison of the whole-genome sequences to a reference strain. Our findings suggest that loss of T3SS gene expression may be a trait common to both CF and non-CF chronic infections.
A common feature of microorganisms that cause chronic infections is a stealthy lifestyle that promotes immune avoidance and host tolerance. During chronic colonization of cystic fibrosis (CF) patients, Pseudomonas aeruginosa acquires numerous adaptations that include reduced expression of some factors, such as motility, O antigen, and the T3SS, and increased expression of other traits, such as biofilm formation. In this study, we report loss of T3SS gene expression in non-CF chronic isolates. This finding suggests that loss of the T3SS may be a common and important trait that contributes to persistence and may open avenues to explore the significance further using non-CF chronic infection models.
Details
- Title: Subtitle
- Genome Sequences of Two Pseudomonas aeruginosa Isolates with Defects in Type III Secretion System Gene Expression from a Chronic Ankle Wound Infection
- Creators
- Sardar Karash - University of IowaRobert Nordell - University of IowaEgon A Ozer - Department of Medicine, Northwestern Fienberg School of Medicine, Chicago, Illinois, USA.Timothy L Yahr - University of Iowa
- Resource Type
- Journal article
- Publication Details
- Microbiology spectrum, Vol.9(1), pp.e0034021-6
- DOI
- 10.1128/Spectrum.00340-21
- PMID
- 34259549
- PMCID
- PMC8552725
- NLM abbreviation
- Microbiol Spectr
- ISSN
- 2165-0497
- eISSN
- 2165-0497
- Grant note
- P30 DK054759 / NIDDK NIH HHS R01 AI055042 / NIAID NIH HHS
- Language
- English
- Date published
- 09/03/2021
- Academic Unit
- Microbiology and Immunology
- Record Identifier
- 9984297433702771
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