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Rodrigues Alves LB, Freitas Neto OCD, Saraiva MDMS, do Monte DFM, de Lima BN, Cabrera JM, Barbosa FDO, Benevides VP, de Lima TS, Campos IC, Rubio MDS, Nascimento CDF, Arantes LCRV, Alves VV, de Almeida AM, Olsen JE, Berchieri Junior A. Salmonella Gallinarum mgtC mutant shows a delayed fowl typhoid progression in chicken. Gene 2024; 892:147827. [PMID: 37748627 DOI: 10.1016/j.gene.2023.147827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 08/29/2023] [Accepted: 09/22/2023] [Indexed: 09/27/2023]
Abstract
Salmonella Gallinarum (SG) provokes fowl typhoid, an infectious disease of acute clinical course that affects gallinaceous of any age and leads to high mortality rates. During the typhoid-like systemic infection of S. Typhimurium (STM) in mice, the bacterium expresses the mgtC gene, which is encoded in the Salmonella Pathogenecity Island - 3 (SPI-3). In this serovar, the function is linked to bacterial replication within macrophages, and its absence attenuates the pathogen. We hypothesized that deleting mgtC from SG genome would alter the microorganism pathogenicity in susceptible commercial poultry in a similar manner. Thus, the present study sought to elucidate the importance of mgtC on SG pathogenicity. For this, a mgtC-mutant lacking S. Gallinarum mutant was constructed (SG ΔmgtC). Its ability to replicate in medium that mimicries the mgtC-related intracellular environment of macrophages as well as in primary macrophages from chicken was evaluated. Moreover, the infection of susceptible chickens was performed to elucidate its pathogenicity and the elicited immune responses by measuring key interleukins by qRT-PCR and the population of macrophages and lymphocytes T CD4+ and CD8+ by means of immunohistochemistry. It was observed that mgtC was required for S. Gallinarum replication in acidified low-Mg2+ media and survival within macrophages. However, unlike its requirement for initial phase of STM infection in mice, lower bacterial counts were only observed at the late stage of macrophage infection without affecting the citotoxicity. Experiments showed that knocking-out the mgtC gene neither altered bacterial uptake by macrophages nor affects bacterial counts in liver and spleen and total chicken mortality. However, plotting a survival curve and analyzing the clinical-pathologic conditions, it was observed a slower progression of the disease in chickens infected by SG ΔmgtC compared to those challenged by the wild-type strain. Furthermore, the mRNA expression of IFN-γ and LITAF were similar between the infected chickens, but higher than in the uninfected group. The same was observed in macrophages and lymphocytes T CD4+ populations. On the other hand, the presence of lymphocytes T CD8+ was increased in the initial phase of the disease provoked by the wild-type strain over the mutant strain. We concluded that the role of mgtC in Fowl Typhoid in susceptible chickens differs from the role in typhoid-like infections in mammals. Thus, the deletion of mgtC gene from S. Gallinarum genome does not affect the overall pathogenicity, but slightly alters the pathogenesis.
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Affiliation(s)
- Lucas Bocchini Rodrigues Alves
- Veterinary Medicine Post-graduation Program (Animal Pathology), Avian Pathology Laboratory, Department of Pathology, Theriogenology, and One Health, School of Agricultural and Veterinary Sciences, Sao Paulo State University (FCAV/Unesp), Jaboticabal, São Paulo, Brazil; Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen (KU), Copenhagen, Denmark.
| | - Oliveiro Caetano de Freitas Neto
- Veterinary Medicine Post-graduation Program (Animal Pathology), Avian Pathology Laboratory, Department of Pathology, Theriogenology, and One Health, School of Agricultural and Veterinary Sciences, Sao Paulo State University (FCAV/Unesp), Jaboticabal, São Paulo, Brazil; Department of Preventive Veterinary Medicine, Veterinary School, Federal University of Minas Gerais (UFMG), Belo Horizonte, Minas Gerais, Brazil.
| | - Mauro de Mesquita Souza Saraiva
- Veterinary Medicine Post-graduation Program (Animal Pathology), Avian Pathology Laboratory, Department of Pathology, Theriogenology, and One Health, School of Agricultural and Veterinary Sciences, Sao Paulo State University (FCAV/Unesp), Jaboticabal, São Paulo, Brazil; Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen (KU), Copenhagen, Denmark
| | - Daniel Farias Marinho do Monte
- Veterinary Medicine Post-graduation Program (Animal Pathology), Avian Pathology Laboratory, Department of Pathology, Theriogenology, and One Health, School of Agricultural and Veterinary Sciences, Sao Paulo State University (FCAV/Unesp), Jaboticabal, São Paulo, Brazil
| | - Bruna Nestlehner de Lima
- Veterinary Medicine Post-graduation Program (Animal Pathology), Avian Pathology Laboratory, Department of Pathology, Theriogenology, and One Health, School of Agricultural and Veterinary Sciences, Sao Paulo State University (FCAV/Unesp), Jaboticabal, São Paulo, Brazil
| | - Julia Memrava Cabrera
- Veterinary Medicine Post-graduation Program (Animal Pathology), Avian Pathology Laboratory, Department of Pathology, Theriogenology, and One Health, School of Agricultural and Veterinary Sciences, Sao Paulo State University (FCAV/Unesp), Jaboticabal, São Paulo, Brazil
| | - Fernanda de Oliveira Barbosa
- Veterinary Medicine Post-graduation Program (Animal Pathology), Avian Pathology Laboratory, Department of Pathology, Theriogenology, and One Health, School of Agricultural and Veterinary Sciences, Sao Paulo State University (FCAV/Unesp), Jaboticabal, São Paulo, Brazil
| | - Valdinete Pereira Benevides
- Veterinary Medicine Post-graduation Program (Animal Pathology), Avian Pathology Laboratory, Department of Pathology, Theriogenology, and One Health, School of Agricultural and Veterinary Sciences, Sao Paulo State University (FCAV/Unesp), Jaboticabal, São Paulo, Brazil; Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen (KU), Copenhagen, Denmark
| | - Túlio Spina de Lima
- Veterinary Medicine Post-graduation Program (Animal Pathology), Avian Pathology Laboratory, Department of Pathology, Theriogenology, and One Health, School of Agricultural and Veterinary Sciences, Sao Paulo State University (FCAV/Unesp), Jaboticabal, São Paulo, Brazil
| | - Isabella Cardeal Campos
- Veterinary Medicine Post-graduation Program (Animal Pathology), Avian Pathology Laboratory, Department of Pathology, Theriogenology, and One Health, School of Agricultural and Veterinary Sciences, Sao Paulo State University (FCAV/Unesp), Jaboticabal, São Paulo, Brazil
| | - Marcela da Silva Rubio
- Veterinary Medicine Post-graduation Program (Animal Pathology), Avian Pathology Laboratory, Department of Pathology, Theriogenology, and One Health, School of Agricultural and Veterinary Sciences, Sao Paulo State University (FCAV/Unesp), Jaboticabal, São Paulo, Brazil
| | - Camila de Fatima Nascimento
- Veterinary Medicine Post-graduation Program (Animal Pathology), Avian Pathology Laboratory, Department of Pathology, Theriogenology, and One Health, School of Agricultural and Veterinary Sciences, Sao Paulo State University (FCAV/Unesp), Jaboticabal, São Paulo, Brazil
| | - Letícia Cury Rocha Veloso Arantes
- Department of Preventive Veterinary Medicine, Veterinary School, Federal University of Minas Gerais (UFMG), Belo Horizonte, Minas Gerais, Brazil
| | - Victória Veiga Alves
- Department of Preventive Veterinary Medicine, Veterinary School, Federal University of Minas Gerais (UFMG), Belo Horizonte, Minas Gerais, Brazil
| | - Adriana Maria de Almeida
- Veterinary Medicine Post-graduation Program (Animal Pathology), Avian Pathology Laboratory, Department of Pathology, Theriogenology, and One Health, School of Agricultural and Veterinary Sciences, Sao Paulo State University (FCAV/Unesp), Jaboticabal, São Paulo, Brazil
| | - John Elmerdahl Olsen
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen (KU), Copenhagen, Denmark
| | - Angelo Berchieri Junior
- Veterinary Medicine Post-graduation Program (Animal Pathology), Avian Pathology Laboratory, Department of Pathology, Theriogenology, and One Health, School of Agricultural and Veterinary Sciences, Sao Paulo State University (FCAV/Unesp), Jaboticabal, São Paulo, Brazil.
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Zhang Y, Liao X, Feng J, Liu D, Chen S, Ding T. Induction of viable but nonculturable Salmonella spp. in liquid eggs by mild heat and subsequent resuscitation. Food Microbiol 2023; 109:104127. [DOI: 10.1016/j.fm.2022.104127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 08/16/2022] [Accepted: 08/31/2022] [Indexed: 11/28/2022]
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Saraiva MDMS, Benevides VP, da Silva NMV, Varani ADM, de Freitas Neto OC, Berchieri Â, Delgado-Suárez EJ, Rocha ADDL, Eguale T, Munyalo JA, Kariuki S, Gebreyes WA, de Oliveira CJB. Genomic and Evolutionary Analysis of Salmonella enterica Serovar Kentucky Sequence Type 198 Isolated From Livestock In East Africa. Front Cell Infect Microbiol 2022; 12:772829. [PMID: 35795189 PMCID: PMC9251186 DOI: 10.3389/fcimb.2022.772829] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 04/20/2022] [Indexed: 11/14/2022] Open
Abstract
Since its emergence in the beginning of the 90’s, multidrug-resistant (MDR) Salmonella enterica subsp. enterica serovar Kentucky has become a significant public health problem, especially in East Africa. This study aimed to investigate the antimicrobial resistance profile and the genotypic relatedness of Salmonella Kentucky isolated from animal sources in Ethiopia and Kenya (n=19). We also investigated population evolutionary dynamics through phylogenetic and pangenome analyses with additional publicly available Salmonella Kentucky ST198 genomes (n=229). All the 19 sequenced Salmonella Kentucky isolates were identified as ST198. Among these isolates, the predominant genotypic antimicrobial resistance profile observed in ten (59.7%) isolates included the aac(3)-Id, aadA7, strA-strB, blaTEM-1B, sul1, and tet(A) genes, which mediated resistance to gentamicin, streptomycin/spectinomycin, streptomycin, ampicillin, sulfamethoxazole and tetracycline, respectively; and gyrA and parC mutations associated to ciprofloxacin resistance. Four isolates harbored plasmid types Incl1 and/or Col8282; two of them carried both plasmids. Salmonella Pathogenicity islands (SPI-1 to SPI-5) were highly conserved in the 19 sequenced Salmonella Kentucky isolates. Moreover, at least one Pathogenicity Island (SPI 1–4, SPI 9 or C63PI) was identified among the 229 public Salmonella Kentucky genomes. The phylogenetic analysis revealed that almost all Salmonella Kentucky ST198 isolates (17/19) stemmed from a single strain that has accumulated ciprofloxacin resistance-mediating mutations. A total of 8,104 different genes were identified in a heterogenic and still open Salmonella Kentucky ST198 pangenome. Considering the virulence factors and antimicrobial resistance genes detected in Salmonella Kentucky, the implications of this pathogen to public health and the epidemiological drivers for its dissemination must be investigated.
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Affiliation(s)
- Mauro de Mesquita Sousa Saraiva
- Department of Pathology, Theriogenology, and One Health, Sao Paulo State University (FCAV-Unesp), Jaboticabal, Brazil
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH, United States
| | - Valdinete Pereira Benevides
- Department of Pathology, Theriogenology, and One Health, Sao Paulo State University (FCAV-Unesp), Jaboticabal, Brazil
| | | | | | - Oliveiro Caetano de Freitas Neto
- Department of Preventive Veterinary Medicine, Veterinary School, Federal University of Minas Gerais (UFMG), Belo Horizonte, Brazil
| | - Ângelo Berchieri
- Department of Pathology, Theriogenology, and One Health, Sao Paulo State University (FCAV-Unesp), Jaboticabal, Brazil
| | - Enrique Jesús Delgado-Suárez
- Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México (UNAM), Mexico City, Mexico
| | - Alan Douglas de Lima Rocha
- Department of Animal Science, Center for Agricultural Sciences, Federal University of Paraiba (CCA/UFPB), Areia, Brazil
| | - Tadesse Eguale
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
| | - Janet Agnes Munyalo
- Centre for Microbiology Research, Kenya Medical Research Institute, Nairobi, Kenya
| | - Samuel Kariuki
- Centre for Microbiology Research, Kenya Medical Research Institute, Nairobi, Kenya
| | - Wondwossen Abebe Gebreyes
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH, United States
- Global One Health Initiative (GOHi), The Ohio State University, Columbus, OH, United States
| | - Celso José Bruno de Oliveira
- Department of Animal Science, Center for Agricultural Sciences, Federal University of Paraiba (CCA/UFPB), Areia, Brazil
- Global One Health Initiative (GOHi), The Ohio State University, Columbus, OH, United States
- *Correspondence: Celso José Bruno de Oliveira,
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Salvail H, Choi J, Groisman EA. Differential synthesis of novel small protein times Salmonella virulence program. PLoS Genet 2022; 18:e1010074. [PMID: 35245279 PMCID: PMC8896665 DOI: 10.1371/journal.pgen.1010074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 02/03/2022] [Indexed: 11/18/2022] Open
Abstract
Gene organization in operons enables concerted transcription of functionally related genes and efficient control of cellular processes. Typically, an operon is transcribed as a polycistronic mRNA that is translated into corresponding proteins. Here, we identify a bicistronic operon transcribed as two mRNAs, yet only one allows translation of both genes. We establish that the novel gene ugtS forms an operon with virulence gene ugtL, an activator of the master virulence regulatory system PhoP/PhoQ in Salmonella enterica serovar Typhimurium. Only the longer ugtSugtL mRNA carries the ugtS ribosome binding site and therefore allows ugtS translation. Inside macrophages, the ugtSugtL mRNA species allowing translation of both genes is produced hours before that allowing translation solely of ugtL. The small protein UgtS controls the kinetics of PhoP phosphorylation by antagonizing UgtL activity, preventing premature activation of a critical virulence program. Moreover, S. enterica serovars that infect cold-blooded animals lack ugtS. Our results establish how foreign gene control of ancestral regulators enables pathogens to time their virulence programs. Pathogens must express their virulence genes at precisely the right time to cause disease. Here, we identify a novel small protein that governs a critical virulence program in the pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium). We establish that the novel small protein UgtS prevents the virulence protein UgtL from activating the master virulence regulator PhoP inside macrophages. S. Typhimurium produces two ugtSugtL mRNAs, but only one of them allows ugtS translation. The absence of ugtS from S. enterica serovars that infect cold-blooded animals raises the possibility of UgtS playing a regulatory role during infection of warm-blooded animals. Our findings establish how a horizontally acquired bicistron enables pathogens to time their virulence programs by controlling ancestral regulators.
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Affiliation(s)
- Hubert Salvail
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, United States of America
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut, United States of America
| | - Jeongjoon Choi
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, United States of America
- Department of Genetics, Yale School of Medicine, New Haven, Connecticut, United States of America
| | - Eduardo A. Groisman
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, United States of America
- Yale Microbial Sciences Institute, West Haven, Connecticut, United States of America
- * E-mail:
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Groisman EA, Duprey A, Choi J. How the PhoP/PhoQ System Controls Virulence and Mg 2+ Homeostasis: Lessons in Signal Transduction, Pathogenesis, Physiology, and Evolution. Microbiol Mol Biol Rev 2021; 85:e0017620. [PMID: 34191587 PMCID: PMC8483708 DOI: 10.1128/mmbr.00176-20] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The PhoP/PhoQ two-component system governs virulence, Mg2+ homeostasis, and resistance to a variety of antimicrobial agents, including acidic pH and cationic antimicrobial peptides, in several Gram-negative bacterial species. Best understood in Salmonella enterica serovar Typhimurium, the PhoP/PhoQ system consists o-regulated gene products alter PhoP-P amounts, even under constant inducing conditions. PhoP-P controls the abundance of hundreds of proteins both directly, by having transcriptional effects on the corresponding genes, and indirectly, by modifying the abundance, activity, or stability of other transcription factors, regulatory RNAs, protease regulators, and metabolites. The investigation of PhoP/PhoQ has uncovered novel forms of signal transduction and the physiological consequences of regulon evolution.
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Affiliation(s)
- Eduardo A. Groisman
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, USA
- Yale Microbial Sciences Institute, West Haven, Connecticut, USA
| | - Alexandre Duprey
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, USA
| | - Jeongjoon Choi
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, USA
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Rubio MDS, Rodrigues Alves LB, Viana GDB, Benevides VP, Spina de Lima T, Santiago Ferreira T, Almeida AMD, Barrow PA, Berchieri Junior A. Heat stress impairs egg production in commercial laying hens infected by fowl typhoid. Avian Pathol 2021; 50:132-137. [PMID: 33146550 DOI: 10.1080/03079457.2020.1845302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Salmonella Gallinarum (SG) is an avian-restricted pathogen that causes fowl typhoid in poultry. Although it has been reported frequently over many decades in poultry flocks worldwide, the microorganism is more commonly associated with poultry in developing countries, particularly those with high ambient temperatures, where the acute form of the disease results in considerable economic losses. A more detailed investigation of environmental factors that affect the course of disease may assist in identifying effective prevention and control measures. Heat stress is known to impair the immunological response to a variety of pathogens and clearly may be an important contributory factor in the prevalence of disease in countries with warm or hot climates. Thus, the objective of the present study was to evaluate the effects of heat stress on chickens infected with SG. For this, light and semi-heavy commercial laying hens were distributed randomly within four groups as follows: infected and non-infected groups in rooms held at ambient temperature, and infected and non-infected groups under heat stress. Clinical signs, egg production, and mortality were recorded daily. Bacteriological counts in liver and spleen samples were estimated at 2, 5, 7, and 14 days post-infection. The results showed that both SG infection and heat stress had similar effects on egg production and a synergistic effect of the two stressors was observed. The data show an interaction between disease and heat stress which could point towards environmental and biosecurity approaches to resolving the possible 30% fall in production observed in such countries.
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Affiliation(s)
- Marcela da Silva Rubio
- School of Agricultural and Veterinary Sciences, Post Graduate Program in Veterinary Medicine and Agricultural and Livestock Microbiology, Sao Paulo State University (FCAV/UNESP), Jaboticabal, Brazil
| | - Lucas Bocchini Rodrigues Alves
- School of Agricultural and Veterinary Sciences, Post Graduate Program in Veterinary Medicine and Agricultural and Livestock Microbiology, Sao Paulo State University (FCAV/UNESP), Jaboticabal, Brazil
| | - Guilherme de Brito Viana
- School of Agricultural and Veterinary Sciences, Post Graduate Program in Veterinary Medicine and Agricultural and Livestock Microbiology, Sao Paulo State University (FCAV/UNESP), Jaboticabal, Brazil
| | - Valdinete Pereira Benevides
- School of Agricultural and Veterinary Sciences, Post Graduate Program in Veterinary Medicine and Agricultural and Livestock Microbiology, Sao Paulo State University (FCAV/UNESP), Jaboticabal, Brazil
| | - Túlio Spina de Lima
- School of Agricultural and Veterinary Sciences, Post Graduate Program in Veterinary Medicine and Agricultural and Livestock Microbiology, Sao Paulo State University (FCAV/UNESP), Jaboticabal, Brazil
| | - Taísa Santiago Ferreira
- School of Agricultural and Veterinary Sciences, Post Graduate Program in Veterinary Medicine and Agricultural and Livestock Microbiology, Sao Paulo State University (FCAV/UNESP), Jaboticabal, Brazil
| | - Adriana Maria de Almeida
- School of Agricultural and Veterinary Sciences, Post Graduate Program in Veterinary Medicine and Agricultural and Livestock Microbiology, Sao Paulo State University (FCAV/UNESP), Jaboticabal, Brazil
| | - Paul Andrew Barrow
- School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington, UK
| | - Angelo Berchieri Junior
- School of Agricultural and Veterinary Sciences, Post Graduate Program in Veterinary Medicine and Agricultural and Livestock Microbiology, Sao Paulo State University (FCAV/UNESP), Jaboticabal, Brazil
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Choi J, Groisman EA. Horizontally acquired regulatory gene activates ancestral regulatory system to promote Salmonella virulence. Nucleic Acids Res 2020; 48:10832-10847. [PMID: 33045730 PMCID: PMC7641745 DOI: 10.1093/nar/gkaa813] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 09/09/2020] [Accepted: 09/17/2020] [Indexed: 01/21/2023] Open
Abstract
Horizontally acquired genes are typically regulated by ancestral regulators. This regulation enables expression of horizontally acquired genes to be coordinated with that of preexisting genes. Here, we report a singular example of the opposite regulation: a horizontally acquired gene that controls an ancestral regulator, thereby promoting bacterial virulence. We establish that the horizontally acquired regulatory gene ssrB is necessary to activate the ancestral regulatory system PhoP/PhoQ of Salmonella enterica serovar Typhimurium (S. Typhimurium) in mildly acidic pH, which S. Typhimurium experiences inside macrophages. SsrB promotes phoP transcription by binding upstream of the phoP promoter. SsrB also increases ugtL transcription by binding to the ugtL promoter region, where it overcomes gene silencing by the heat-stable nucleoid structuring protein H-NS, enhancing virulence. The largely non-pathogenic species S. bongori failed to activate PhoP/PhoQ in mildly acidic pH because it lacks both the ssrB gene and the SsrB binding site in the target promoter. Low Mg2+ activated PhoP/PhoQ in both S. bongori and ssrB-lacking S. Typhimurium, indicating that the SsrB requirement for PhoP/PhoQ activation is signal-dependent. By controlling the ancestral genome, horizontally acquired genes are responsible for more crucial abilities, including virulence, than currently thought.
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Affiliation(s)
- Jeongjoon Choi
- Department of Microbial Pathogenesis, Yale School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA
| | - Eduardo A Groisman
- Department of Microbial Pathogenesis, Yale School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA.,Yale Microbial Sciences Institute, P.O. Box 27389, West Haven, CT 06516, USA
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