FNR Regulates the Expression of Important Virulence Factors Contributing to the Pathogenicity of Avian Pathogenic Escherichia coli
Avian pathogenic Escherichia coli (APEC) is the etiologic agent of colibacillosis, an important cause of morbidity and mortality in poultry. Though, many virulence factors associated with APEC pathogenicity are known, their regulation remains unclear. FNR (fumarate and nitrate reduction) is a well-k...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2017-06-01
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| Series: | Frontiers in Cellular and Infection Microbiology |
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| Online Access: | http://journal.frontiersin.org/article/10.3389/fcimb.2017.00265/full |
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| author | Nicolle L. Barbieri Jessica A. Vande Vorde Alison R. Baker Fabiana Horn Ganwu Li Catherine M. Logue Lisa K. Nolan Lisa K. Nolan |
| author_facet | Nicolle L. Barbieri Jessica A. Vande Vorde Alison R. Baker Fabiana Horn Ganwu Li Catherine M. Logue Lisa K. Nolan Lisa K. Nolan |
| author_sort | Nicolle L. Barbieri |
| collection | DOAJ |
| description | Avian pathogenic Escherichia coli (APEC) is the etiologic agent of colibacillosis, an important cause of morbidity and mortality in poultry. Though, many virulence factors associated with APEC pathogenicity are known, their regulation remains unclear. FNR (fumarate and nitrate reduction) is a well-known global regulator that works as an oxygen sensor and has previously been described as a virulence regulator in bacterial pathogens. The goal of this study was to examine the role of FNR in the regulation of APEC virulence factors, such as Type I fimbriae, and processes such as adherence and invasion, type VI secretion, survival during oxidative stress, and growth in iron-restricted environments. To accomplish this goal, APEC O1, a well-characterized, highly virulent, and fully sequenced strain of APEC harboring multiple virulence mechanisms, some of which are plasmid-linked, was compared to its FNR mutant for expression of various virulence traits. Deletion of FNR was found to affect APEC O1's adherence, invasion and expression of ompT, a plasmid-encoded outer membrane protein, type I fimbriae, and aatA, encoding an autotransporter. Indeed, the fnr− mutant showed an 8-fold reduction in expression of type I fimbriae and a highly significant (P < 0.0001) reduction in expression of fimA, ompT (plasmid-borne), and aatA. FNR was also found to regulate expression of the type VI secretion system, affecting the expression of vgrG. Further, FNR was found to be important to APEC O1's growth in iron-deficient media and survival during oxidative stress with the mutant showing a 4-fold decrease in tolerance to oxidative stress, as compared to the wild type. Thus, our results suggest that FNR functions as an important regulator of APEC virulence. |
| first_indexed | 2024-04-14T01:35:20Z |
| format | Article |
| id | doaj.art-fcf25b8a72d34702ac5cc54011bdd826 |
| institution | Directory Open Access Journal |
| issn | 2235-2988 |
| language | English |
| last_indexed | 2024-04-14T01:35:20Z |
| publishDate | 2017-06-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Cellular and Infection Microbiology |
| spelling | doaj.art-fcf25b8a72d34702ac5cc54011bdd8262022-12-22T02:20:00ZengFrontiers Media S.A.Frontiers in Cellular and Infection Microbiology2235-29882017-06-01710.3389/fcimb.2017.00265248732FNR Regulates the Expression of Important Virulence Factors Contributing to the Pathogenicity of Avian Pathogenic Escherichia coliNicolle L. Barbieri0Jessica A. Vande Vorde1Alison R. Baker2Fabiana Horn3Ganwu Li4Catherine M. Logue5Lisa K. Nolan6Lisa K. Nolan7Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State UniversityAmes, IA, United StatesDepartment of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State UniversityAmes, IA, United StatesDepartment of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State UniversityAmes, IA, United StatesDepartamento de Biofísica, Universidade Federal do Rio Grande do SulPorto Alegre, BrazilDepartment of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State UniversityAmes, IA, United StatesDepartment of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State UniversityAmes, IA, United StatesDepartment of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State UniversityAmes, IA, United StatesDepartment of Infectious Disease, College of Veterinary Medicine, University of GeorgiaAthens, GeorgiaAvian pathogenic Escherichia coli (APEC) is the etiologic agent of colibacillosis, an important cause of morbidity and mortality in poultry. Though, many virulence factors associated with APEC pathogenicity are known, their regulation remains unclear. FNR (fumarate and nitrate reduction) is a well-known global regulator that works as an oxygen sensor and has previously been described as a virulence regulator in bacterial pathogens. The goal of this study was to examine the role of FNR in the regulation of APEC virulence factors, such as Type I fimbriae, and processes such as adherence and invasion, type VI secretion, survival during oxidative stress, and growth in iron-restricted environments. To accomplish this goal, APEC O1, a well-characterized, highly virulent, and fully sequenced strain of APEC harboring multiple virulence mechanisms, some of which are plasmid-linked, was compared to its FNR mutant for expression of various virulence traits. Deletion of FNR was found to affect APEC O1's adherence, invasion and expression of ompT, a plasmid-encoded outer membrane protein, type I fimbriae, and aatA, encoding an autotransporter. Indeed, the fnr− mutant showed an 8-fold reduction in expression of type I fimbriae and a highly significant (P < 0.0001) reduction in expression of fimA, ompT (plasmid-borne), and aatA. FNR was also found to regulate expression of the type VI secretion system, affecting the expression of vgrG. Further, FNR was found to be important to APEC O1's growth in iron-deficient media and survival during oxidative stress with the mutant showing a 4-fold decrease in tolerance to oxidative stress, as compared to the wild type. Thus, our results suggest that FNR functions as an important regulator of APEC virulence.http://journal.frontiersin.org/article/10.3389/fcimb.2017.00265/fullAPECFNRvirulence regulationplasmid-linked virulence genesouter membrane protein |
| spellingShingle | Nicolle L. Barbieri Jessica A. Vande Vorde Alison R. Baker Fabiana Horn Ganwu Li Catherine M. Logue Lisa K. Nolan Lisa K. Nolan FNR Regulates the Expression of Important Virulence Factors Contributing to the Pathogenicity of Avian Pathogenic Escherichia coli Frontiers in Cellular and Infection Microbiology APEC FNR virulence regulation plasmid-linked virulence genes outer membrane protein |
| title | FNR Regulates the Expression of Important Virulence Factors Contributing to the Pathogenicity of Avian Pathogenic Escherichia coli |
| title_full | FNR Regulates the Expression of Important Virulence Factors Contributing to the Pathogenicity of Avian Pathogenic Escherichia coli |
| title_fullStr | FNR Regulates the Expression of Important Virulence Factors Contributing to the Pathogenicity of Avian Pathogenic Escherichia coli |
| title_full_unstemmed | FNR Regulates the Expression of Important Virulence Factors Contributing to the Pathogenicity of Avian Pathogenic Escherichia coli |
| title_short | FNR Regulates the Expression of Important Virulence Factors Contributing to the Pathogenicity of Avian Pathogenic Escherichia coli |
| title_sort | fnr regulates the expression of important virulence factors contributing to the pathogenicity of avian pathogenic escherichia coli |
| topic | APEC FNR virulence regulation plasmid-linked virulence genes outer membrane protein |
| url | http://journal.frontiersin.org/article/10.3389/fcimb.2017.00265/full |
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