1
|
Middendorf PS, Zomer AL, Bergval IL, Jacobs-Reitsma WF, den Besten HMW, Abee T. Host associations of Campylobacter jejuni and Campylobacter coli isolates carrying the L-fucose or d-glucose utilization cluster. Int J Food Microbiol 2024; 425:110855. [PMID: 39191191 DOI: 10.1016/j.ijfoodmicro.2024.110855] [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: 03/16/2024] [Revised: 07/06/2024] [Accepted: 08/03/2024] [Indexed: 08/29/2024]
Abstract
Campylobacter was considered asaccharolytic, but is now known to carry saccharide metabolization pathways for L-fucose and d-glucose. We hypothesized that these clusters are beneficial for Campylobacter niche adaptation and may help establish human infection. We investigated the distribution of d-glucose and L-fucose clusters among ∼9600 C. jejuni and C. coli genomes of different isolation sources in the Netherlands, the United Kingdom, the United States of America and Finland. The L-fucose utilization cluster was integrated at the same location in all C. jejuni and C. coli genomes, and was flanked by the genes rpoB, rpoC, rspL, repsG and fusA, which are associated with functions in transcription as well as translation and in acquired drug resistance. In contrast, the flanking regions of the d-glucose utilization cluster were variable among the isolates, and integration sites were located within one of the three different 16S23S ribosomal RNA areas of the C. jejuni and C. coli genomes. In addition, we investigated whether acquisition of the L-fucose utilization cluster could be due to horizontal gene transfer between the two species and found three isolates for which this was the case: one C. jejuni isolate carrying a C. coli L-fucose cluster, and two C. coli isolates which carried a C. jejuni L-fucose cluster. Furthermore, L-fucose utilization cluster alignments revealed multiple frameshift mutations, most of which were commonly found in the non-essential genes for L-fucose metabolism, namely, Cj0484 and Cj0489. These findings support our hypothesis that the L-fucose cluster was integrated multiple times across the C. coli/C. jejuni phylogeny. Notably, association analysis using the C. jejuni isolates from the Netherlands showed a significant correlation between human C. jejuni isolates and C. jejuni isolates carrying the L-fucose utilization cluster. This correlation was even stronger when the Dutch isolates were combined with the isolates from the UK, the USA and Finland. No such correlations were observed for C. coli or for the d-glucose cluster for both species. This research provides insight into the spread and host associations of the L-fucose and d-glucose utilization clusters in C. jejuni and C. coli, and the potential benefits in human infection and/or proliferation in humans, conceivably after transmission from any reservoir.
Collapse
Affiliation(s)
- Pjotr S Middendorf
- Food Microbiology, Wageningen University and Research, Wageningen, Netherlands; National Institute for Public Health and the Environment, Bilthoven, Netherlands
| | - Aldert L Zomer
- Faculty of Veterinary Medicine, Department of Infectious Diseases and Immunology, Utrecht University, Utrecht, Netherlands; WHO Collaborating Center for Campylobacter/OIE Reference Laboratory for Campylobacteriosis, Utrecht, Netherlands
| | - Indra L Bergval
- National Institute for Public Health and the Environment, Bilthoven, Netherlands
| | | | | | - Tjakko Abee
- Food Microbiology, Wageningen University and Research, Wageningen, Netherlands.
| |
Collapse
|
2
|
Bowlin MQ, Lieber AD, Long AR, Gray MJ. C-terminal Poly-histidine Tags Alter Escherichia coli Polyphosphate Kinase Activity and Susceptibility to Inhibition. J Mol Biol 2024; 436:168651. [PMID: 38866092 PMCID: PMC11297678 DOI: 10.1016/j.jmb.2024.168651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 06/05/2024] [Accepted: 06/06/2024] [Indexed: 06/14/2024]
Abstract
In Escherichia coli, many environmental stressors trigger polyphosphate (polyP) synthesis by polyphosphate kinase (PPK1), including heat, nutrient restriction, toxic compounds, and osmotic imbalances. PPK1 is essential for virulence in many pathogens and has been the target of multiple screens for small molecule inhibitors that might serve as new anti-virulence drugs. However, the mechanisms by which PPK1 activity and polyP synthesis are regulated are poorly understood. Our previous attempts to uncover PPK1 regulatory elements resulted in the discovery of PPK1* mutants, which accumulate more polyP in vivo, but do not produce more in vitro. In attempting to further characterize these mutant enzymes, we discovered that the most commonly-used PPK1 purification method - Ni-affinity chromatography using a C-terminal poly-histidine tag - altered intrinsic aspects of the PPK1 enzyme, including specific activity, oligomeric state, and kinetic values. We developed an alternative purification strategy using a C-terminal C-tag which did not have these effects. Using this strategy, we were able to demonstrate major differences in the in vitro response of PPK1 to 5-aminosalicylic acid, a known PPK1 inhibitor, and observed several key differences between the wild-type and PPK1* enzymes, including changes in oligomeric distribution, increased enzymatic activity, and increased resistance to both product (ADP) and substrate (ATP) inhibition, that help to explain their in vivo effects. Importantly, our results indicate that the C-terminal poly-histidine tag is inappropriate for purification of PPK1, and that any in vitro studies or inhibitor screens performed with such tags need to be reconsidered in that light.
Collapse
Affiliation(s)
- Marvin Q Bowlin
- Department of Microbiology, University of Alabama at Birmingham Heersink School of Medicine, Birmingham, AL, USA
| | - Avery D Lieber
- Department of Microbiology, University of Alabama at Birmingham Heersink School of Medicine, Birmingham, AL, USA
| | - Abagail R Long
- Department of Microbiology, University of Alabama at Birmingham Heersink School of Medicine, Birmingham, AL, USA
| | - Michael J Gray
- Department of Microbiology, University of Alabama at Birmingham Heersink School of Medicine, Birmingham, AL, USA.
| |
Collapse
|
3
|
Guan J, Jakob U. The Protein Scaffolding Functions of Polyphosphate. J Mol Biol 2024; 436:168504. [PMID: 38423453 DOI: 10.1016/j.jmb.2024.168504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 01/31/2024] [Accepted: 02/21/2024] [Indexed: 03/02/2024]
Abstract
Inorganic polyphosphate (polyP), one of the first high-energy compound on earth, defies its extreme compositional and structural simplicity with an astoundingly wide array of biological activities across all domains of life. However, the underlying mechanism of such functional pleiotropy remains largely elusive. In this review, we will summarize recent studies demonstrating that this simple polyanion stabilizes protein folding intermediates and scaffolds select native proteins. These functions allow polyP to act as molecular chaperone that protects cells against protein aggregation, as pro-amyloidogenic factor that accelerates both physiological and disease-associated amyloid formation, and as a modulator of liquid-liquid phase separation processes. These activities help to explain polyP's known roles in bacterial stress responses and pathogenicity, provide the mechanistic foundation for its potential role in human neurodegenerative diseases, and open a new direction regarding its influence on gene expression through condensate formation. We will highlight critical unanswered questions and point out potential directions that will help to further understand the pleiotropic functions of this ancient and ubiquitous biopolymer.
Collapse
Affiliation(s)
- Jian Guan
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Ursula Jakob
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA; Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, MI, USA.
| |
Collapse
|
4
|
Corrales D, Alcántara C, Zúñiga M, Monedero V. Ppx1 putative exopolyphosphatase is essential for polyphosphate accumulation in Lacticaseibacillus paracasei. Appl Environ Microbiol 2024; 90:e0229023. [PMID: 38619267 PMCID: PMC11107151 DOI: 10.1128/aem.02290-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 03/27/2024] [Indexed: 04/16/2024] Open
Abstract
The linear polymer polyphosphate (poly-P) is present across all three domains of life and serves diverse physiological functions. The enzyme polyphosphate kinase (Ppk) is responsible for poly-P synthesis, whereas poly-P degradation is carried out by the enzyme exopolyphosphatase (Ppx). In many Lactobacillaceae, the Ppk-encoding gene (ppk) is found clustered together with two genes encoding putative exopolyphosphatases (ppx1 and ppx2) each having different domain compositions, with the gene order ppx1-ppk-ppx2. However, the specific function of these ppx genes remains unexplored. An in-frame deletion of ppx1 in Lacticaseibacillus paracasei BL23 resulted in bacteria unable to accumulate poly-P, whereas the disruption of ppx2 did not affect poly-P synthesis. The expression of ppk was not altered in the Δppx1 strain, and poly-P synthesis in this strain was only restored by expressing ppx1 in trans. Moreover, no poly-P synthesis was observed when ppk was expressed from a plasmid in the Δppx1 strain. Purified Ppx2 exhibited in vitro exopolyphosphatase activity, whereas no in vitro enzymatic activity could be demonstrated for Ppx1. This observation corresponds with the absence in Ppx1 of conserved motifs essential for catalysis found in characterized exopolyphosphatases. Furthermore, assays with purified Ppk and Ppx1 evidenced that Ppx1 enhanced Ppk activity. These results demonstrate that Ppx1 is essential for poly-P synthesis in Lc. paracasei and have unveiled, for the first time, an unexpected role of Ppx1 exopolyphosphatase in poly-P synthesis.IMPORTANCEPoly-P is a pivotal molecular player in bacteria, participating in a diverse array of processes ranging from stress resilience to pathogenesis while also serving as a functional component in probiotic bacteria. The synthesis of poly-P is tightly regulated, but the underlying mechanisms remain incompletely elucidated. Our study sheds light on the distinctive role played by the two exopolyphosphatases (Ppx) found in the Lactobacillaceae bacterial group, of relevance in food and health. This particular group is noteworthy for possessing two Ppx enzymes, supposedly involved in poly-P degradation. Remarkably, our investigation uncovers an unprecedented function of Ppx1 in Lacticaseibacillus paracasei, where its absence leads to the total cessation of poly-P synthesis, paralleling the impact observed upon eliminating the poly-P forming enzyme, poly-P kinase. Unlike the anticipated role as a conventional exopolyphosphatase, Ppx1 demonstrates an unexpected function. Our results added a layer of complexity to our understanding of poly-P dynamics in bacteria.
Collapse
Affiliation(s)
- Daniela Corrales
- Instituto de Agroquímica y Tecnología de Alimentos (IATA-CSIC), Paterna, Spain
| | - Cristina Alcántara
- Instituto de Agroquímica y Tecnología de Alimentos (IATA-CSIC), Paterna, Spain
| | - Manuel Zúñiga
- Instituto de Agroquímica y Tecnología de Alimentos (IATA-CSIC), Paterna, Spain
| | - Vicente Monedero
- Instituto de Agroquímica y Tecnología de Alimentos (IATA-CSIC), Paterna, Spain
| |
Collapse
|
5
|
Wei Z, Zhang Y, Duan X, Fan Y. Enhancing L-Asparagine Bioproduction Efficiency Through L-Asparagine Synthetase and Polyphosphate Kinase-Coupled Conversion and ATP Regeneration. Appl Biochem Biotechnol 2024:10.1007/s12010-024-04856-z. [PMID: 38358456 DOI: 10.1007/s12010-024-04856-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/04/2024] [Indexed: 02/16/2024]
Abstract
L-Asparagine, a crucial amino acid widely used in both food and medicine, presents pollution-related and side reaction challenges when prepared using chemical synthesis method. Although biotransformation methods offer significant advantages such as high efficiency and mild reaction conditions, they also entail increased costs due to the need for ATP supplementation. This study aimed to address the challenges associated with biopreparation of L-asparagine. Firstly, the functionality and characteristics of recombinant L-asparagine synthetase enzymes derived from Escherichia coli and Lactobacillus salivarius were evaluated to determine their practical applicability. Subsequently, recombinant expression of polyphosphate kinase from Erysipelotrichaceae bacterium was conducted. A reaction system for L-asparagine synthesis was established using a dual enzyme-coupled conversion approach. Under the optimal reaction conditions, a maximum yield of 11.67 g/L of L-asparagine was achieved, with an 88.43% conversion rate, representing a 5.03-fold increase compared to the initial conversion conditions. Notably, the initial addition of ATP was reduced to only 5.66% of the theoretical demand, indicating the effectiveness of our ATP regeneration system. These findings highlight the potential of our approach in enhancing the efficiency of L-asparagine preparation, offering promising prospects for the food and medical industries.
Collapse
Affiliation(s)
- Zijia Wei
- College of Light Industry and Food Engineering, Nanjing Forestry University, Nanjing, 210037, Jiangsu, China
| | - Yuhua Zhang
- College of Light Industry and Food Engineering, Nanjing Forestry University, Nanjing, 210037, Jiangsu, China
| | - Xuguo Duan
- College of Light Industry and Food Engineering, Nanjing Forestry University, Nanjing, 210037, Jiangsu, China.
| | - Yucheng Fan
- College of Light Industry and Food Engineering, Nanjing Forestry University, Nanjing, 210037, Jiangsu, China
| |
Collapse
|
6
|
Chen X, Xue J, Dong X, Lu P. Uncovering virulence factors in Cronobacter sakazakii: insights from genetic screening and proteomic profiling. Appl Environ Microbiol 2023; 89:e0102823. [PMID: 37750707 PMCID: PMC10617496 DOI: 10.1128/aem.01028-23] [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: 06/20/2023] [Accepted: 07/15/2023] [Indexed: 09/27/2023] Open
Abstract
The increasing problem of antibiotic resistance has driven the search for virulence factors in pathogenic bacteria, which can serve as targets for the development of new antibiotics. Although whole-genome Tn5 transposon mutagenesis combined with phenotypic assays has been a widely used approach, its efficiency remains low due to labor-intensive processes. In this study, we aimed to identify specific genes and proteins associated with the virulence of Cronobacter sakazakii, a pathogenic bacterium known for causing severe infections, particularly in infants and immunocompromised individuals. By employing a combination of genetic screening, comparative proteomics, and in vivo validation using zebrafish and rat models, we rapidly screened highly virulent strains and identified two genes, rcsA and treR, as potential regulators of C. sakazakii toxicity toward zebrafish and rats. Proteomic profiling revealed upregulated proteins upon knockout of rcsA and treR, including FabH, GshA, GppA, GcvH, IhfB, RfaC, MsyB, and three unknown proteins. Knockout of their genes significantly weakened bacterial virulence, confirming their role as potential virulence factors. Our findings contribute to understanding the pathogenicity of C. sakazakii and provide insights into the development of targeted interventions and therapies against this bacterium.IMPORTANCEThe emergence of antibiotic resistance in pathogenic bacteria has become a critical global health concern, necessitating the identification of virulence factors as potential targets for the development of new antibiotics. This study addresses the limitations of conventional approaches by employing a combination of genetic screening, comparative proteomics, and in vivo validation to rapidly identify specific genes and proteins associated with the virulence of Cronobacter sakazakii, a highly pathogenic bacterium responsible for severe infections in vulnerable populations. The identification of two genes, rcsA and treR, as potential regulators of C. sakazakii toxicity toward zebrafish and rats and the proteomic profiling upon knockout of rcsA and treR provides novel insights into the mechanisms underlying bacterial virulence. The findings contribute to our understanding of C. sakazakii's pathogenicity, shed light on the regulatory pathways involved in bacterial virulence, and offer potential targets for the development of novel interventions against this highly virulent bacterium.
Collapse
Affiliation(s)
- Xi Chen
- Tianjin Eye Hospital, Tianjin Eye Institute,Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin, China
| | - Juan Xue
- Institute of Infection and Immunity, Taihe Hospital, Hubei University of Medicine, Shiyan, China
| | - Xiaoli Dong
- Tianjin Eye Hospital, Tianjin Eye Institute,Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin, China
| | - Ping Lu
- Tianjin Eye Hospital, Tianjin Eye Institute,Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin, China
| |
Collapse
|
7
|
Carbonero A, Maldonado-Iniesta A, Trujillo Y, Perea J, Riofrío M, Garcia-Bocanegra I, Borge C. Identification of genes associated with environmental persistence in Campylobacter jejuni and Campylobacter coli isolates from processing in a broiler abattoir. Vet Res Commun 2022; 46:1325-1330. [PMID: 36094751 PMCID: PMC9684268 DOI: 10.1007/s11259-022-09981-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 08/01/2022] [Indexed: 10/14/2022]
Abstract
The aim of this study was to determine the prevalence of the htrA, htrB and ppk1 genes -all of which are related to environmental persistence- in C. jejuni and C. coli isolates obtained from abattoir samples at the arrival of broilers (initial stage) and in meat products after processing (final stage). A total of 119 DNA extracts (55 C. jejuni and 64 C. coli) were included in the study. Identification of genes was performed by conventional PCR (one for each gene). The overall prevalence was 40.3%, 93.3% and 68.9% for the htrA, htrB and ppk1 genes, respectively. Statistically significant differences were found (p < 0.05) between prevalence of C. jejuni and C. coli for all three genes. In C. coli the prevalence was significantly higher for the htrA (p = 0.007) and htrB (p = 0.015) genes, while ppk1 gene prevalence was significantly higher in C. jejuni (p < 0.001). In addition, statistically significant increase in the frequency of htrA (p = 0.007) and htrB (p = 0.013) genes in the final product compared to broilers on arrival at the abattoir was observed in C. jejuni, but not in C. coli. These results suggest that htrA and htrB genes are involved in environmental persistence of Campylobacter jejuni.
Collapse
Affiliation(s)
- A Carbonero
- Department of Animal Health, University of Cordoba, Animal Health Building, Campus Universitario de Rabanales, 14014, Córdoba, Spain
| | - A Maldonado-Iniesta
- Department of Animal Health, University of Cordoba, Animal Health Building, Campus Universitario de Rabanales, 14014, Córdoba, Spain
| | - Y Trujillo
- Department of Animal Health, University of Cordoba, Animal Health Building, Campus Universitario de Rabanales, 14014, Córdoba, Spain
| | - J Perea
- Department of Animal Production, University of Cordoba, Production Animal Building, Campus Universitario de Rabanales, 14014, Córdoba, Spain.
| | - M Riofrío
- Andalusian Health Service, Health Center Polígono del Guadalquivir, 14013, Cordoba, Spain
| | - I Garcia-Bocanegra
- Department of Animal Health, University of Cordoba, Animal Health Building, Campus Universitario de Rabanales, 14014, Córdoba, Spain
| | - C Borge
- Department of Animal Health, University of Cordoba, Animal Health Building, Campus Universitario de Rabanales, 14014, Córdoba, Spain
| |
Collapse
|
8
|
Ma L, Feng J, Zhang J, Lu X. Campylobacter biofilms. Microbiol Res 2022; 264:127149. [DOI: 10.1016/j.micres.2022.127149] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 07/26/2022] [Accepted: 07/26/2022] [Indexed: 11/27/2022]
|
9
|
Li S, Lam J, Souliotis L, Alam MT, Constantinidou C. Posttranscriptional Regulation in Response to Different Environmental Stresses in Campylobacter jejuni. Microbiol Spectr 2022; 10:e0020322. [PMID: 35678555 PMCID: PMC9241687 DOI: 10.1128/spectrum.00203-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 05/10/2022] [Indexed: 11/20/2022] Open
Abstract
The survival strategies that Campylobacter jejuni (C. jejuni) employ throughout its transmission and infection life cycles remain largely elusive. Specifically, there is a lack of understanding about the posttranscriptional regulation of stress adaptations resulting from small noncoding RNAs (sRNAs). Published C. jejuni sRNAs have been discovered in specific conditions but with limited insights into their biological activities. Many more sRNAs are yet to be discovered as they may be condition-dependent. Here, we have generated transcriptomic data from 21 host- and transmission-relevant conditions. The data uncovered transcription start sites, expression patterns and posttranscriptional regulation during various stress conditions. This data set helped predict a list of putative sRNAs. We further explored the sRNAs' biological functions by integrating differential gene expression analysis, coexpression analysis, and genome-wide sRNA target prediction. The results showed that the C. jejuni gene expression was influenced primarily by nutrient deprivation and food storage conditions. Further exploration revealed a putative sRNA (CjSA21) that targeted tlp1 to 4 under food processing conditions. tlp1 to 4 are transcripts that encode methyl-accepting chemotaxis proteins (MCPs), which are responsible for chemosensing. These results suggested CjSA21 inhibits chemotaxis and promotes survival under food processing conditions. This study presents the broader research community with a comprehensive data set and highlights a novel sRNA as a potential chemotaxis inhibitor. IMPORTANCE The foodborne pathogen C. jejuni is a significant challenge for the global health care system. It is crucial to investigate C. jejuni posttranscriptional regulation by small RNAs (sRNAs) in order to understand how it adapts to different stress conditions. However, limited data are available for investigating sRNA activity under stress. In this study, we generate gene expression data of C. jejuni under 21 stress conditions. Our data analysis indicates that one of the novel sRNAs mediates the adaptation to food processing conditions. Results from our work shed light on the posttranscriptional regulation of C. jejuni and identify an sRNA associated with food safety.
Collapse
Affiliation(s)
- Stephen Li
- Warwick Medical School, University of Warwick, Coventry, United Kingdom
| | - Jenna Lam
- Warwick Medical School, University of Warwick, Coventry, United Kingdom
| | | | - Mohammad Tauqeer Alam
- Department of Biology, College of Science, United Arab Emirates University, Al-Ain, United Arab Emirates
| | | |
Collapse
|
10
|
Progress Report: Antimicrobial Drug Discovery in the Resistance Era. Pharmaceuticals (Basel) 2022; 15:ph15040413. [PMID: 35455410 PMCID: PMC9030565 DOI: 10.3390/ph15040413] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 03/23/2022] [Accepted: 03/24/2022] [Indexed: 02/05/2023] Open
Abstract
Antibiotic resistance continues to be a most serious threat to public health. This situation demands that the scientific community increase their efforts for the discovery of alternative strategies to circumvent the problems associated with conventional small molecule therapeutics. The Global Antimicrobial Resistance and Use Surveillance System (GLASS) Report (published in June 2021) discloses the rapidly increasing number of bacterial infections that are mainly caused by antimicrobial-resistant bacteria. These concerns have initiated various government agencies and other organizations to educate the public regarding the appropriate use of antibiotics. This review discusses a brief highlight on the timeline of antimicrobial drug discovery with a special emphasis on the historical development of antimicrobial resistance. In addition, new antimicrobial targets and approaches, recent developments in drug screening, design, and delivery were covered. This review also discusses the emergence and roles of various antibiotic adjuvants and combination therapies while shedding light on current challenges and future perspectives. Overall, the emergence of resistant microbial strains has challenged drug discovery but their efforts to develop alternative technologies such as nanomaterials seem to be promising for the future.
Collapse
|
11
|
Du Y, Wang X, Han Z, Hua Y, Yan K, Zhang B, Zhao W, Wan C. Polyphosphate Kinase 1 Is a Pathogenesis Determinant in Enterohemorrhagic Escherichia coli O157:H7. Front Microbiol 2021; 12:762171. [PMID: 34777317 PMCID: PMC8578739 DOI: 10.3389/fmicb.2021.762171] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Accepted: 10/08/2021] [Indexed: 11/16/2022] Open
Abstract
The ppk1 gene encodes polyphosphate kinase (PPK1), which is the major catalytic enzyme that Escherichia coli utilizes to synthesize inorganic polyphosphate (polyP). The aim of this study was to explore the role of PPK1 in the pathogenesis of Enterohemorrhagic E. coli O157:H7 (EHEC O157:H7). An isogenic in-frame ppk1 deletion mutant (Δppk1) and ppk1 complemented mutant (Cppk1) were constructed and characterized in comparison to wild-type (WT) EHEC O157:H7 strain EDL933w by microscope observation and growth curve analysis. Survival rates under heat stress and acid tolerance, both of which the bacteria would face during pathogenesis, were compared among the three strains. LoVo cells and a murine model of intestinal colitis were used as the in vitro and in vivo models, respectively, to evaluate the effect of PPK1 on adhesion and invasion during the process of pathogenesis. Real-time reverse-transcription PCR of regulatory gene rpoS, adhesion gene eae, and toxin genes stx1 and stx2 was carried out to corroborate the results from the in vitro and in vivo models. The ppk1 deletion mutant exhibited disrupted polyP levels, but not morphology and growth characteristics. The survival rate of the Δppk1 strain under stringent environmental conditions was lower as compared with WT and Cppk1. The in vitro assays showed that deletion of the ppk1 gene reduced the adhesion, formation of attaching and effacing (A/E) lesions, and invasive ability of EHEC O157:H7. Moreover, the virulence of the Δppk1 in BALB/c mice was weaker as compared with the other two strains. Additionally, mRNA expression of rpoS, eae, stx1 and stx2 were consistent with the in vitro and in vivo results. In conclusion: EHEC O157:H7 requires PPK1 for both survival under harsh environmental conditions and virulence in vivo.
Collapse
Affiliation(s)
- Yanli Du
- School of Medical Technology and Nursing, Shenzhen Polytechnic, Shenzhen, China
| | - Xiangyu Wang
- Department of Gastroenterology, The First Affiliated Hospital of Shenzhen University, Shenzhen Second People's Hospital, Shenzhen, China.,Department of Microbiology, School of Public Health, Southern Medical University, Guangzhou, China
| | - Zongli Han
- Department of Neurosurgery, Peking University Shenzhen Hospital, Shenzhen, China
| | - Ying Hua
- Department of Microbiology, School of Public Health, Southern Medical University, Guangzhou, China
| | - Kaina Yan
- Department of Microbiology, School of Public Health, Southern Medical University, Guangzhou, China
| | - Bao Zhang
- Department of Microbiology, School of Public Health, Southern Medical University, Guangzhou, China
| | - Wei Zhao
- Department of Microbiology, School of Public Health, Southern Medical University, Guangzhou, China
| | - Chengsong Wan
- Department of Microbiology, School of Public Health, Southern Medical University, Guangzhou, China.,Key Laboratory of Tropical Disease Research of Guangdong Province, Guangzhou, China
| |
Collapse
|
12
|
Biofilm Formation Ability of Arcobacter-like and Campylobacter Strains under Different Conditions and on Food Processing Materials. Microorganisms 2021; 9:microorganisms9102017. [PMID: 34683338 PMCID: PMC8538277 DOI: 10.3390/microorganisms9102017] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 09/09/2021] [Accepted: 09/21/2021] [Indexed: 11/23/2022] Open
Abstract
Campylobacter jejuni is the most frequent cause of bacterial gastrointestinal food-borne infection worldwide. The transmission of Campylobacter and Arcobacter-like species is often made possible by their ability to adhere to various abiotic surfaces. This study is focused on monitoring the biofilm ability of 69 strains of Campylobacter spp. and lesser described species of the Arcobacteraceae family isolated from food, water, and clinical samples within the Czech Republic. Biofilm formation was monitored and evaluated under an aerobic/microaerophilic atmosphere after cultivation for 24 or 72 h depending on the surface material. An overall higher adhesion ability was observed in arcobacters. A chi-squared test showed no association between the origin of the strains and biofilm activity (p > 0.05). Arcobacter-like species are able to form biofilms under microaerophilic and aerobic conditions; however, they prefer microaerophilic environments. Biofilm formation has already been demonstrated at refrigerator temperatures (5 °C). Arcobacters also showed higher biofilm formation ability at the temperature of 30 °C. This is in contrast to Campylobacter jejuni NP 2896, which showed higher biofilm formation ability at temperatures of 5–30 °C. Overall, the results demonstrated the biofilm formation ability of many strains, which poses a considerable risk to the food industry, medical practice, and human health.
Collapse
|
13
|
Chaves M, Vazquez-Valverde D, Fernández-Jaramillo H, Arias-Echandi ML. The ability of Aliarcobacter butzleri strains isolated from foods of animal origin in Costa Rica to form biofilm. Ital J Food Saf 2021; 10:9020. [PMID: 34268142 PMCID: PMC8256308 DOI: 10.4081/ijfs.2021.9020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Accepted: 03/22/2021] [Indexed: 11/23/2022] Open
Abstract
Aliarcobacter butzleri is a zoonotic emerging food and waterborne pathogen widely distributed in nature. It is present in food processing environments and can easily be spread through the food industry because of its ability to form biofilm. The aim of this work was to determine the ability of strains isolated in Costa Rica from different food matrixes of animal origin to form biofilm. Thirty-eight A. butzleri strains previously isolated and identified from animal origin products were analyzed using the method described by Stepmovic et al. (2000), in three culture broths, brain heart infusion broth, Boer broth and Houf broth. Results showed that 67% of poultry origin strains, 62.5% of meat origin strains and just 8% of milk origin strains showed ability to form biofilm. The findings of this study confirm the adherence ability of A. butzleri to form biofilm, a characteristic that can promote dispersion and cross contamination along food industry processing lines.
Collapse
Affiliation(s)
- Marco Chaves
- Microbiology Faculty and Tropical Diseases Research Center (CIET), University of Costa Rica, San José, Costa Rica
| | - Daniel Vazquez-Valverde
- Microbiology Faculty and Tropical Diseases Research Center (CIET), University of Costa Rica, San José, Costa Rica
| | | | - María Laura Arias-Echandi
- Microbiology Faculty and Tropical Diseases Research Center (CIET), University of Costa Rica, San José, Costa Rica
| |
Collapse
|
14
|
A Dual-Specificity Inhibitor Targets Polyphosphate Kinase 1 and 2 Enzymes To Attenuate Virulence of Pseudomonas aeruginosa. mBio 2021; 12:e0059221. [PMID: 34126765 PMCID: PMC8262977 DOI: 10.1128/mbio.00592-21] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The opportunistic pathogen Pseudomonas aeruginosa is a leading cause of nosocomial infections, which are becoming increasingly difficult to treat due to antibiotic resistance. Polyphosphate (polyP) plays a key role in P. aeruginosa virulence, stress response, and antibiotic tolerance, suggesting an attractive drug target. Here, we show that the small molecule gallein disrupts polyphosphate homeostasis by inhibiting all members of both polyphosphate kinase (PPK) families (PPK1 and PPK2) encoded by P. aeruginosa, demonstrating dual-specificity PPK inhibition for the first time. Inhibitor treatment phenocopied ppk deletion to reduce cellular polyP accumulation and attenuate biofilm formation, motility, and pyoverdine and pyocyanin production. Most importantly, gallein attenuated P. aeruginosa virulence in a Caenorhabditis elegans infection model and synergized with antibiotics while exhibiting negligible toxicity toward the nematodes or HEK293T cells, suggesting our discovery of dual-specificity PPK inhibitors as a promising starting point for the development of new antivirulence therapeutics.
Collapse
|
15
|
Cui C, Kong M, Wang Y, Zhou C, Ming H. Characterization of polyphosphate kinases for the synthesis of GSH with ATP regeneration from AMP. Enzyme Microb Technol 2021; 149:109853. [PMID: 34311890 DOI: 10.1016/j.enzmictec.2021.109853] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 05/24/2021] [Accepted: 06/09/2021] [Indexed: 11/17/2022]
Abstract
Polyphosphate kinase (PPK) is important for industrial processes involving ATP regeneration. While a variety of methods have been reported for regenerating ATP from ADP, few have explored enzyme catalyzed ATP regeneration from cheaper and stable AMP. In this work, PPKs from different sources were expressed and their catalytic activity were tested at different reaction temperatures, reaction pH and with different polyphosphate (polyPn) types. The ATP regeneration system for glutathione (GSH) synthesis was established using a single PPK capable of phosphorylating AMP to synthesize ATP from AMP and short chain polyPn. GSH yield was obtained using adenosine mono-, di- and triphosphates, which confirmed the flexibility of our constructed ATP regeneration system coupled with GSH synthesis via bifunctional GSH synthase. Finally, optimization of the GSH synthesis yielded conversion value above 80 %. Overall, these results illustrate that PPK is suitable for a broader range of substrates than previously expected, and has great untapped potential for applications involving ATP regeneration.
Collapse
Affiliation(s)
- Caixia Cui
- Department of Biopharmaceutical Sciences, School of Life Science and Technology, Xinxiang Medical University, Xinxiang 453003, PR China.
| | - Mengyuan Kong
- Department of Biopharmaceutical Sciences, School of Life Science and Technology, Xinxiang Medical University, Xinxiang 453003, PR China
| | - Yihan Wang
- Department of Biopharmaceutical Sciences, School of Life Science and Technology, Xinxiang Medical University, Xinxiang 453003, PR China
| | - Chenyan Zhou
- Department of Biopharmaceutical Sciences, School of Life Science and Technology, Xinxiang Medical University, Xinxiang 453003, PR China
| | - Hong Ming
- Department of Biopharmaceutical Sciences, School of Life Science and Technology, Xinxiang Medical University, Xinxiang 453003, PR China.
| |
Collapse
|
16
|
Inorganic Polyphosphate in Host and Microbe Biology. Trends Microbiol 2021; 29:1013-1023. [PMID: 33632603 DOI: 10.1016/j.tim.2021.02.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 01/29/2021] [Accepted: 02/01/2021] [Indexed: 12/15/2022]
Abstract
Inorganic polyphosphate (polyP) is produced by both bacteria and their eukaryotic hosts, and it appears to play multiple important roles in the interactions between those organisms. However, the detailed mechanisms of how polyP synthesis is regulated in bacteria, and how it influences both bacterial and host biology, remain largely unexplored. In this review, we examine recent developments in the understanding of how bacteria regulate the synthesis of polyP, what roles polyP plays in controlling virulence in pathogenic bacteria, and the effects of polyP on the mammalian immune system, as well as progress on developing drugs that may be able to target bacterial polyP synthesis as novel means of treating infectious disease.
Collapse
|
17
|
Whelan MVX, Simpson JC, Ó Cróinín T. A novel high-content screening approach for the elucidation of C. jejuni biofilm composition and integrity. BMC Microbiol 2021; 21:2. [PMID: 33397288 PMCID: PMC7784365 DOI: 10.1186/s12866-020-02062-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 11/23/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Campylobacter jejuni is the leading cause of bacterial gastroenteritis worldwide and the main source of infection is contaminated chicken meat. Although this important human pathogen is an obligate microaerophile, it must survive atmospheric oxygen conditions to allow transmission from contaminated chicken meat to humans. It is becoming increasingly evident that formation of biofilm plays a key role in the survival of this organism for extended periods on poultry products. We have recently demonstrated a novel inducible model for the study of adherent C. jejuni biofilm formation under aerobic conditions. By taking advantage of supercoiling mediated gene regulation, incubation of C. jejuni with subinhibitory concentrations of the Gyrase B inhibitor novobiocin was shown to promote the consistent formation of metabolically active adherent biofilm. RESULTS In this study, we implement this model in conjunction with the fluorescent markers: TAMRA (live cells) and SytoX (dead cells, eDNA) to develop a novel systematic high-content imaging approach and describe how it can be implemented to gain quantifiable information about the integrity and extracellular polymeric substance (EPS) composition of adherent C. jejuni biofilm in aerobic conditions. We show that this produces a model with a consistent, homogenous biofilm that can be induced and used to screen a range of inhibitors of biofilm adherence and matrix formation. CONCLUSIONS This model allows for the first time a high throughput analysis of C. jejuni biofilms which will be invaluable in enabling researchers to develop mechanisms to disrupt these biofilms and reduce the viability of these bacteria under aerobic conditions.
Collapse
Affiliation(s)
- Matthew V X Whelan
- School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Jeremy C Simpson
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Tadhg Ó Cróinín
- School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin 4, Ireland.
| |
Collapse
|
18
|
Gautam LK, Sharma P, Capalash N. Attenuation of Acinetobacter baumannii virulence by inhibition of polyphosphate kinase 1 with repurposed drugs. Microbiol Res 2020; 242:126627. [PMID: 33131985 DOI: 10.1016/j.micres.2020.126627] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 09/27/2020] [Accepted: 10/14/2020] [Indexed: 12/28/2022]
Abstract
Acinetobacter baumannii is clinically one of the most significant pathogens, especially in intensive care settings, because of its multidrug-resistance (MDR). Repurposing of high-affinity drugs is a faster and more plausible approach for combating the emergence of MDR and to tackle bacterial infections. This study was aimed to evaluate the approved drugs potentially inhibiting A. baumannii PPK1 (AbPPK1) mediated synthesis of polyphosphates (polyP). Based on virtual screening, molecular dynamic simulation, and CD spectroscopy for thermal stability, two stable ligands, etoposide and genistein, were found with promising contours for further investigation. Following in vitro inhibition of AbPPK1, the efficacy of selected drugs was further tested against virulence traits of A. baumannii. These drugs significantly reduced the biofilm formation, surface motility in A. baumannii and led to decreased survival under desiccation. In addition to inhibition of PPK1, both drugs increased the expression of polyP degrading enzyme, exopolyphosphatase (PPX), that might be responsible for the decrease in the total cellular polyP. Since polyP modulates the virulence factors in bacteria, destabilization of the polyP pool by these drugs seems particularly striking for their therapeutic applications against A. baumannii.
Collapse
Affiliation(s)
- Lalit Kumar Gautam
- Department of Biotechnology, Panjab University, BMS Block-I, Sector- 25, Chandigarh, 160014, India
| | - Prince Sharma
- Department of Microbiology, Panjab University, BMS Block-I, Sector- 25, Chandigarh, 160014, India
| | - Neena Capalash
- Department of Biotechnology, Panjab University, BMS Block-I, Sector- 25, Chandigarh, 160014, India.
| |
Collapse
|
19
|
Interactions between DksA and Stress-Responsive Alternative Sigma Factors Control Inorganic Polyphosphate Accumulation in Escherichia coli. J Bacteriol 2020; 202:JB.00133-20. [PMID: 32341074 DOI: 10.1128/jb.00133-20] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 04/21/2020] [Indexed: 01/24/2023] Open
Abstract
Bacteria synthesize inorganic polyphosphate (polyP) in response to a variety of different stress conditions. polyP protects bacteria by acting as a protein-stabilizing chaperone, metal chelator, or regulator of protein function, among other mechanisms. However, little is known about how stress signals are transmitted in the cell to lead to increased polyP accumulation. Previous work in the model enterobacterium Escherichia coli has indicated that the RNA polymerase-binding regulatory protein DksA is required for polyP synthesis in response to nutrient limitation stress. In this work, I set out to characterize the role of DksA in polyP regulation in more detail. I found that overexpression of DksA increases cellular polyP content (explaining the long-mysterious phenotype of dksA overexpression rescuing growth of a dnaK mutant at high temperatures) and characterized the roles of known functional residues of DksA in this process, finding that binding to RNA polymerase is required but that none of the other functions of DksA appear to be necessary. Transcriptomics revealed genome-wide transcriptional changes upon nutrient limitation, many of which were affected by DksA, and follow-up experiments identified complex interactions between DksA and the stress-sensing alternative sigma factors FliA, RpoN, and RpoE that impact polyP production, indicating that regulation of polyP synthesis is deeply entwined in the multifactorial stress response network of E. coli IMPORTANCE Inorganic polyphosphate (polyP) is an evolutionarily ancient, widely conserved biopolymer required for stress resistance and pathogenesis in diverse bacteria, but we do not understand how its synthesis is regulated. In this work, I gained new insights into this process by characterizing the role of the transcriptional regulator DksA in polyP regulation in Escherichia coli and identifying previously unknown links between polyP synthesis and the stress-responsive alternative sigma factors FliA, RpoN, and RpoE.
Collapse
|
20
|
Soro AB, Whyte P, Bolton DJ, Tiwari BK. Strategies and novel technologies to control Campylobacter in the poultry chain: A review. Compr Rev Food Sci Food Saf 2020; 19:1353-1377. [PMID: 33337085 DOI: 10.1111/1541-4337.12544] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 01/06/2020] [Accepted: 01/15/2020] [Indexed: 12/15/2022]
Abstract
Campylobacteriosis is one of the most common bacterial infections worldwide causing economic costs. The high prevalence of Campylobacter spp. in poultry meat is a result of several contamination and cross-contamination sources through the production chain. Moreover, survival mechanisms, such as biofilm formation, viable but nonculturable state, and antimicrobial resistance, enable its persistence during food processing. Therefore, mitigation strategies are necessary in order to avoid and/or inactivate Campylobacter at farm, abattoir, industry, and retail level. In this review, a number of potential strategies and novel technologies that could reduce the prevalence of Campylobacter in poultry meat have been identified and evaluated to provide a useful overview. At farm level for instance, biosecurity, bacteriocins, probiotics, feed and water additives, bacteriophages, and vaccination could potentially reduce colonization in chicken flocks. However, current technologies used in the chicken slaughter and processing industry may be less effective against this foodborne pathogen. Novel technologies and strategies such as cold plasma, ultraviolet light, high-intensity light pulses, pulsed electric fields, antimicrobials, and modified atmosphere packaging are discussed in this review for reducing Campylobacter contamination. Although these measures have achieved promising results, most have not been integrated within processing operations due to a lack of knowledge or an unwillingness to implement these into existing processing systems. Furthermore, a combination of existing and novel strategies might be required to decrease the prevalence of this pathogen in poultry meat and enhance food safety. Therefore, further research will be essential to assess the effectiveness of all these strategies.
Collapse
Affiliation(s)
- Arturo B Soro
- Department of Food Chemistry and Technology, Teagasc Food Research Centre, Ashtown, Ireland.,UCD School of Veterinary Medicine, University College Dublin, Belfield, Ireland
| | - Paul Whyte
- UCD School of Veterinary Medicine, University College Dublin, Belfield, Ireland
| | - Declan J Bolton
- Department of Food Safety, Teagasc Food Research Centre, Ashtown, Ireland
| | - Brijesh K Tiwari
- Department of Food Chemistry and Technology, Teagasc Food Research Centre, Ashtown, Ireland
| |
Collapse
|
21
|
Tram G, Day CJ, Korolik V. Bridging the Gap: A Role for Campylobacter jejuni Biofilms. Microorganisms 2020; 8:E452. [PMID: 32210099 PMCID: PMC7143964 DOI: 10.3390/microorganisms8030452] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 03/19/2020] [Accepted: 03/19/2020] [Indexed: 12/23/2022] Open
Abstract
Campylobacter jejuni is the leading cause of bacterial gastroenteritis in the developed world. Cases of Campylobacteriosis are common, as the organism is an avian commensal and is passed on to humans through contaminated poultry meat, water, and food preparation areas. Although typically a fastidious organism, C. jejuni can survive outside the avian intestinal tract until it is able to reach a human host. It has long been considered that biofilms play a key role in transmission of this pathogen. The aim of this review is to examine factors that trigger biofilm formation in C. jejuni. A range of environmental elements have been shown to initiate biofilm formation, which are then affected by a suite of intrinsic factors. We also aim to further investigate the role that biofilms may play in the life cycle of this organism.
Collapse
Affiliation(s)
| | - Christopher J. Day
- Institute for Glycomics, Griffith University, Southport, Queensland 4222, Australia;
| | - Victoria Korolik
- Institute for Glycomics, Griffith University, Southport, Queensland 4222, Australia;
| |
Collapse
|
22
|
Phosphate Transporter PstSCAB of Campylobacter jejuni Is a Critical Determinant of Lactate-Dependent Growth and Colonization in Chickens. J Bacteriol 2020; 202:JB.00716-19. [PMID: 31932316 DOI: 10.1128/jb.00716-19] [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] [Received: 11/21/2019] [Accepted: 12/17/2019] [Indexed: 12/17/2022] Open
Abstract
Campylobacter jejuni causes acute gastroenteritis worldwide and is transmitted primarily through poultry, in which it is often a commensal member of the intestinal microbiota. Previous transcriptome sequencing (RNA-Seq) experiment showed that transcripts from an operon encoding a high-affinity phosphate transporter (PstSCAB) of C. jejuni were among the most abundant when the bacterium was grown in chickens. Elevated levels of the pstSCAB mRNA were also identified in an RNA-Seq experiment from human infection studies. In this study, we explore the role of PstSCAB in the biology and colonization potential of C. jejuni Our results demonstrate that cells lacking PstSCAB survive poorly in stationary phase, in nutrient-limiting media, and under osmotic conditions reflective of those in the chicken. Polyphosphate levels in the mutant cells were elevated at stationary phase, consistent with alterations in expression of polyphosphate metabolism genes. The mutant strain was highly attenuated for colonization of newly hatched chicks, with levels of bacteria at several orders of magnitude below wild-type levels. Mutant and wild type grew similarly in complex media, but the pstS::kan mutant exhibited a significant growth defect in minimal medium supplemented with l-lactate, postulated as a carbon source in vivo Poor growth in lactate correlated with diminished expression of acetogenesis pathway genes previously demonstrated as important for colonizing chickens. The phosphate transport system is thus essential for diverse aspects of C. jejuni physiology and in vivo fitness and survival.IMPORTANCE Campylobacter jejuni causes millions of human gastrointestinal infections annually, with poultry a major source of infection. Due to the emergence of multidrug resistance in C. jejuni, there is need to identify alternative ways to control this pathogen. Genes encoding the high-affinity phosphate transporter PstSCAB are highly expressed by C. jejuni in chickens and humans. In this study, we address the role of PstSCAB on chicken colonization and other C. jejuni phenotypes. PstSCAB is required for colonization in chicken, metabolism and survival under different stress responses, and during growth on lactate, a potential growth substrate in chickens. Our study highlights that PstSCAB may be an effective target to develop mechanisms for controlling bacterial burden in both chicken and human.
Collapse
|
23
|
Negretti NM, Clair G, Talukdar PK, Gourley CR, Huynh S, Adkins JN, Parker CT, Corneau CM, Konkel ME. Campylobacter jejuni Demonstrates Conserved Proteomic and Transcriptomic Responses When Co-cultured With Human INT 407 and Caco-2 Epithelial Cells. Front Microbiol 2019; 10:755. [PMID: 31031730 PMCID: PMC6470190 DOI: 10.3389/fmicb.2019.00755] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Accepted: 03/26/2019] [Indexed: 12/21/2022] Open
Abstract
Major foodborne bacterial pathogens, such as Campylobacter jejuni, have devised complex strategies to establish and foster intestinal infections. For more than two decades, researchers have used immortalized cell lines derived from human intestinal tissue to dissect C. jejuni-host cell interactions. Known from these studies is that C. jejuni virulence is multifactorial, requiring a coordinated response to produce virulence factors that facilitate host cell interactions. This study was initiated to identify C. jejuni proteins that contribute to adaptation to the host cell environment and cellular invasion. We demonstrated that C. jejuni responds to INT 407 and Caco-2 cells in a similar fashion at the cellular and molecular levels. Active protein synthesis was found to be required for C. jejuni to maximally invade these host cells. Proteomic and transcriptomic approaches were then used to define the protein and gene expression profiles of C. jejuni co-cultured with cells. By focusing on those genes showing increased expression by C. jejuni when co-cultured with epithelial cells, we discovered that C. jejuni quickly adapts to co-culture with epithelial cells by synthesizing gene products that enable it to acquire specific amino acids for growth, scavenge for inorganic molecules including iron, resist reactive oxygen/nitrogen species, and promote host cell interactions. Based on these findings, we selected a subset of the genes involved in chemotaxis and the regulation of flagellar assembly and generated C. jejuni deletion mutants for phenotypic analysis. Binding and internalization assays revealed significant differences in the interaction of C. jejuni chemotaxis and flagellar regulatory mutants. The identification of genes involved in C. jejuni adaptation to culture with host cells provides new insights into the infection process.
Collapse
Affiliation(s)
- Nicholas M. Negretti
- School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, WA, United States
| | - Geremy Clair
- Integrative Omics, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Prabhat K. Talukdar
- School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, WA, United States
| | - Christopher R. Gourley
- School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, WA, United States
| | - Steven Huynh
- Produce Safety and Microbiology, United States Department of Agriculture-Agricultural Research Service, Albany, CA, United States
| | - Joshua N. Adkins
- Integrative Omics, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Craig T. Parker
- Produce Safety and Microbiology, United States Department of Agriculture-Agricultural Research Service, Albany, CA, United States
| | - Colby M. Corneau
- School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, WA, United States
| | - Michael E. Konkel
- School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, WA, United States
| |
Collapse
|
24
|
Gautam LK, Sharma P, Capalash N. Bacterial Polyphosphate Kinases Revisited: Role in Pathogenesis and Therapeutic Potential. Curr Drug Targets 2019; 20:292-301. [DOI: 10.2174/1389450119666180801120231] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 06/02/2018] [Accepted: 07/31/2018] [Indexed: 11/22/2022]
Abstract
Bacterial infections have always been an unrestrained challenge to the medical community due to the rise of multi-drug tolerant and resistant strains. Pioneering work on Escherichia coli polyphosphate kinase (PPK) by Arthur Kornberg has generated great interest in this polyphosphate (PolyP) synthesizing enzyme. PPK has wide distribution among pathogens and is involved in promoting pathogenesis, stress management and susceptibility to antibiotics. Further, the absence of a PPK orthologue in humans makes it a potential drug target. This review covers the functional and structural aspects of polyphosphate kinases in bacterial pathogens. A description of molecules being designed against PPKs has been provided, challenges associated with PPK inhibitor design are highlighted and the strategies to enable development of efficient drug against this enzyme have also been discussed.
Collapse
Affiliation(s)
- Lalit Kumar Gautam
- Department of Biotechnology, Panjab University, BMS Block-I, Sector- 25, Chandigarh, 160014, India
| | - Prince Sharma
- Department of Microbiology, Panjab University, BMS Block-I, Sector- 25, Chandigarh, 160014, India
| | - Neena Capalash
- Department of Biotechnology, Panjab University, BMS Block-I, Sector- 25, Chandigarh, 160014, India
| |
Collapse
|
25
|
Pokhrel A, Lingo JC, Wolschendorf F, Gray MJ. Assaying for Inorganic Polyphosphate in Bacteria. J Vis Exp 2019. [PMID: 30735204 DOI: 10.3791/58818] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Inorganic polyphosphate (polyP) is a biological polymer found in cells from all domains of life, and is required for virulence and stress response in many bacteria. There are a variety of methods for quantifying polyP in biological materials, many of which are either labor-intensive or insensitive, limiting their usefulness. We present here a streamlined method for polyP quantification in bacteria, using a silica membrane column extraction optimized for rapid processing of multiple samples, digestion of polyP with the polyP-specific exopolyphosphatase ScPPX, and detection of the resulting free phosphate with a sensitive ascorbic acid-based colorimetric assay. This procedure is straightforward, inexpensive, and allows reliable polyP quantification in diverse bacterial species. We present representative polyP quantification from the Gram-negative bacterium (Escherichia coli), the Gram-positive lactic acid bacterium (Lactobacillus reuteri), and the mycobacterial species (Mycobacterium smegmatis). We also include a simple protocol for nickel affinity purification of mg quantities of ScPPX, which is not currently commercially available.
Collapse
Affiliation(s)
- Arya Pokhrel
- Department of Microbiology, University of Alabama at Birmingham
| | - Jordan C Lingo
- Division of Infectious Diseases, University of Alabama at Birmingham
| | | | - Michael J Gray
- Department of Microbiology, University of Alabama at Birmingham;
| |
Collapse
|
26
|
Chandrashekhar K, Srivastava V, Hwang S, Jeon B, Ryu S, Rajashekara G. Transducer-Like Protein in Campylobacter jejuni With a Role in Mediating Chemotaxis to Iron and Phosphate. Front Microbiol 2018; 9:2674. [PMID: 30505293 PMCID: PMC6250842 DOI: 10.3389/fmicb.2018.02674] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 10/19/2018] [Indexed: 01/20/2023] Open
Abstract
Chemotaxis-mediated motility enables Campylobacter jejuni to navigate through complex environmental gradients and colonize diverse niches. C. jejuni is known to possess several methyl accepting chemotaxis proteins (MCPs), also called transducer-like proteins (Tlps). While the role of some of the Tlps in chemotaxis has been identified, their regulation and role in virulence is still not very clear. Here, we investigated the contribution of Tlp2 to C. jejuni chemotaxis, stress survival and colonization of the chicken gastrointestinal tract. The Δtlp2 deletion mutant showed decreased chemotaxis toward aspartate, pyruvate, inorganic phosphate (Pi), and iron (FeSO4). Transcriptional analysis of tlp2 with a promoter fusion reporter assay revealed that the tlp2 promoter (P tlp2 ) was induced by Pi and iron, both in the ferrous (Fe2+) and ferric form (Fe3+). RT-PCR analysis using overlapping primers indicated that the phoX gene, located immediately downstream of tlp2, is co-transcribed with tlp2. A transcription start site was identified at 53 bp upstream of the tlp2 start codon. The Δtlp2 mutant showed decreased colonization of the chicken gastrointestinal tract. Collectively, our findings revealed that the tlp2 plays a role in C. jejuni pathogenesis and colonization in the chicken host and its expression is regulated by iron.
Collapse
Affiliation(s)
- Kshipra Chandrashekhar
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, OH, United States
| | - Vishal Srivastava
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, OH, United States
| | - Sunyoung Hwang
- Department of Food and Animal Biotechnology – Department of Agricultural Biotechnology, Center for Agricultural Biomaterials, Seoul National University, Seoul, South Korea
| | - Byeonghwa Jeon
- School of Public Health, University of Alberta, Edmonton, AB, Canada
| | - Sangryeol Ryu
- Department of Food and Animal Biotechnology – Department of Agricultural Biotechnology, Center for Agricultural Biomaterials, Seoul National University, Seoul, South Korea
| | - Gireesh Rajashekara
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, OH, United States
| |
Collapse
|
27
|
Nocek BP, Khusnutdinova AN, Ruszkowski M, Flick R, Burda M, Batyrova K, Brown G, Mucha A, Joachimiak A, Berlicki Ł, Yakunin AF. Structural Insights into Substrate Selectivity and Activity of Bacterial Polyphosphate Kinases. ACS Catal 2018. [DOI: 10.1021/acscatal.8b03151] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Boguslaw P. Nocek
- Midwest Center for Structural Genomics and Structural Biology Center, Department of Biosciences, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Anna N. Khusnutdinova
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON M5S 3E5, Canada
| | - Milosz Ruszkowski
- Synchrotron Radiation Research Section of MCL, National Cancer Institute, Argonne, Illinois 60439, United States
| | - Robert Flick
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON M5S 3E5, Canada
| | - Malgorzata Burda
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wroclaw University of Science and Technology, 50-370 Wroclaw, Poland
| | - Khorcheska Batyrova
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON M5S 3E5, Canada
| | - Greg Brown
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON M5S 3E5, Canada
| | - Artur Mucha
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wroclaw University of Science and Technology, 50-370 Wroclaw, Poland
| | - Andrzej Joachimiak
- Midwest Center for Structural Genomics and Structural Biology Center, Department of Biosciences, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Łukasz Berlicki
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wroclaw University of Science and Technology, 50-370 Wroclaw, Poland
| | - Alexander F. Yakunin
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON M5S 3E5, Canada
| |
Collapse
|
28
|
Bhaskar A, De Piano C, Gelman E, McKinney JD, Dhar N. Elucidating the role of (p)ppGpp in mycobacterial persistence against antibiotics. IUBMB Life 2018; 70:836-844. [PMID: 30092117 DOI: 10.1002/iub.1888] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 05/23/2018] [Indexed: 01/05/2023]
Abstract
Bacterial persistence, the ability of bacteria to survive high concentrations of antibiotics for extended periods of time, is an important contributing factor to therapy failure and development of chronic and recurrent infections. Several recent studies have suggested that this persistence is mediated primarily by (p)ppGpp, through its interactions with toxin-antitoxin modules and polyphosphates. In this study, we address whether these key players play a role in mycobacterial persistence against antibiotics. We targeted these specific pathways in Mycobacterium smegmatis by constructing deletion strains of (p)ppGpp synthetase/hydrolase (relA), polyphosphate kinases (ppk1 and ppk2), exopolyphosphatases (ppx1 and ppx2), and the lon protease. None of these mutant strains exhibited altered levels of persisters against isoniazid and ciprofloxacin, when compared with wild-type strain. Even under conditions in which the stringent response usually gets activated, these strains displayed wild-type persister levels. Interestingly, we also found that unlike Escherichia coli, maintaining M. smegmatis in exponential phase by repeated passaging does not eliminate persisters suggesting that at least against the antibiotics tested, stationary-phase dependent persisters (type I) are not the major contributors. Thus, our data demonstrate that multiple mechanisms of antibiotic persistence exist and that these vary widely among different bacterial species. © 2018 IUBMB Life, 70(9):836-844, 2018.
Collapse
Affiliation(s)
- Ashima Bhaskar
- Laboratory of Microbiology and Microtechnology, School of Life Sciences, Swiss Federal Institute of Technology in Lausanne (EPFL), Lausanne, Switzerland
| | - Cyntia De Piano
- Laboratory of Microbiology and Microtechnology, School of Life Sciences, Swiss Federal Institute of Technology in Lausanne (EPFL), Lausanne, Switzerland
| | - Ekaterina Gelman
- Laboratory of Microbiology and Microtechnology, School of Life Sciences, Swiss Federal Institute of Technology in Lausanne (EPFL), Lausanne, Switzerland
| | - John D McKinney
- Laboratory of Microbiology and Microtechnology, School of Life Sciences, Swiss Federal Institute of Technology in Lausanne (EPFL), Lausanne, Switzerland
| | - Neeraj Dhar
- Laboratory of Microbiology and Microtechnology, School of Life Sciences, Swiss Federal Institute of Technology in Lausanne (EPFL), Lausanne, Switzerland
| |
Collapse
|
29
|
Bashatwah RM, Khanfar MA, Bardaweel SK. Discovery of potent polyphosphate kinase 1 (PPK1) inhibitors using structure-based exploration of PPK1Pharmacophoric space coupled with docking analyses. J Mol Recognit 2018; 31:e2726. [DOI: 10.1002/jmr.2726] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2017] [Revised: 04/03/2018] [Accepted: 04/13/2018] [Indexed: 01/30/2023]
Affiliation(s)
- Rasha M. Bashatwah
- Department of Pharmaceutical Sciences, School of Pharmacy; The University of Jordan; Amman Jordan
| | - Mohammad A. Khanfar
- Heinrich-Heine-Universitaet Duesseldorf; InstitutfuerPharmazeutische and MedizinischeChemie; Duesseldorf Germany
| | - Sanaa K. Bardaweel
- Department of Pharmaceutical Sciences, School of Pharmacy; The University of Jordan; Amman Jordan
| |
Collapse
|
30
|
Rudat AK, Pokhrel A, Green TJ, Gray MJ. Mutations in Escherichia coli Polyphosphate Kinase That Lead to Dramatically Increased In Vivo Polyphosphate Levels. J Bacteriol 2018; 200:e00697-17. [PMID: 29311274 PMCID: PMC5826030 DOI: 10.1128/jb.00697-17] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 12/20/2017] [Indexed: 11/20/2022] Open
Abstract
Bacteria synthesize inorganic polyphosphate (polyP) in response to a wide variety of stresses, and production of polyP is essential for stress response and survival in many important pathogens and bacteria used in biotechnological processes. However, surprisingly little is known about the molecular mechanisms that control polyP synthesis. We have therefore developed a novel genetic screen that specifically links growth of Escherichia coli to polyP synthesis, allowing us to isolate mutations leading to enhanced polyP production. Using this system, we have identified mutations in the polyP-synthesizing enzyme polyP kinase (PPK) that lead to dramatic increases in in vivo polyP synthesis but do not substantially affect the rate of polyP synthesis by PPK in vitro These mutations are distant from the PPK active site and found in interfaces between monomers of the PPK tetramer. We have also shown that high levels of polyP lead to intracellular magnesium starvation. Our results provide new insights into the control of bacterial polyP accumulation and suggest a simple, novel strategy for engineering bacteria with increased polyP contents.IMPORTANCE PolyP is an ancient, universally conserved biomolecule and is important for stress response, energy metabolism, and virulence in a remarkably broad range of microorganisms. PolyP accumulation by bacteria is also important in biotechnology applications. For example, it is critical to enhanced biological phosphate removal (EBPR) from wastewater. Understanding how bacteria control polyP synthesis is therefore of broad importance in both the fields of bacterial pathogenesis and biological engineering. Using Escherichia coli as a model organism, we have identified the first known mutations in polyP kinase that lead to increases in cellular polyP content.
Collapse
Affiliation(s)
- Amanda K Rudat
- Department of Microbiology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Arya Pokhrel
- Department of Microbiology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Todd J Green
- Department of Microbiology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Michael J Gray
- Department of Microbiology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| |
Collapse
|
31
|
Bronowski C, Mustafa K, Goodhead I, James CE, Nelson C, Lucaci A, Wigley P, Humphrey TJ, Williams NJ, Winstanley C. Campylobacter jejuni transcriptome changes during loss of culturability in water. PLoS One 2017; 12:e0188936. [PMID: 29190673 PMCID: PMC5708674 DOI: 10.1371/journal.pone.0188936] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 11/15/2017] [Indexed: 12/21/2022] Open
Abstract
Background Water serves as a potential reservoir for Campylobacter, the leading cause of bacterial gastroenteritis in humans. However, little is understood about the mechanisms underlying variations in survival characteristics between different strains of C. jejuni in natural environments, including water. Results We identified three Campylobacter jejuni strains that exhibited variability in their ability to retain culturability after suspension in tap water at two different temperatures (4°C and 25°C). Of the three, strains C. jejuni M1 exhibited the most rapid loss of culturability whilst retaining viability. Using RNAseq transcriptomics, we characterised C. jejuni M1 gene expression in response to suspension in water by analyzing bacterial suspensions recovered immediately after introduction into water (Time 0), and from two sampling time/temperature combinations where considerable loss of culturability was evident, namely (i) after 24 h at 25°C, and (ii) after 72 h at 4°C. Transcript data were compared with a culture-grown control. Some gene expression characteristics were shared amongst the three populations recovered from water, with more genes being up-regulated than down. Many of the up-regulated genes were identified in the Time 0 sample, whereas the majority of down-regulated genes occurred in the 25°C (24 h) sample. Conclusions Variations in expression were found amongst genes associated with oxygen tolerance, starvation and osmotic stress. However, we also found upregulation of flagellar assembly genes, accompanied by down-regulation of genes involved in chemotaxis. Our data also suggested a switch from secretion via the sec system to via the tat system, and that the quorum sensing gene luxS may be implicated in the survival of strain M1 in water. Variations in gene expression also occurred in accessory genome regions. Our data suggest that despite the loss of culturability, C. jejuni M1 remains viable and adapts via specific changes in gene expression.
Collapse
Affiliation(s)
- Christina Bronowski
- Institute of Infection and Global Health, University of Liverpool, Liverpool, United Kingdom
| | - Kasem Mustafa
- Institute of Infection and Global Health, University of Liverpool, Liverpool, United Kingdom
| | - Ian Goodhead
- School of Environment and Life Sciences, University of Salford, Salford, United Kingdom
| | - Chloe E. James
- School of Environment and Life Sciences, University of Salford, Salford, United Kingdom
| | - Charlotte Nelson
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Anita Lucaci
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Paul Wigley
- Institute of Infection and Global Health, University of Liverpool, Liverpool, United Kingdom
| | - Tom J. Humphrey
- Medical Microbiology and Infectious Diseases, School of Medicine, Swansea University, Swansea, United Kingdom
| | - Nicola J. Williams
- Institute of Infection and Global Health, University of Liverpool, Liverpool, United Kingdom
| | - Craig Winstanley
- Institute of Infection and Global Health, University of Liverpool, Liverpool, United Kingdom
- * E-mail:
| | | |
Collapse
|
32
|
Hyperbiofilm Formation by Bordetella pertussis Strains Correlates with Enhanced Virulence Traits. Infect Immun 2017; 85:IAI.00373-17. [PMID: 28893915 DOI: 10.1128/iai.00373-17] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 09/03/2017] [Indexed: 01/01/2023] Open
Abstract
Pertussis, or whooping cough, caused by the obligate human pathogen Bordetella pertussis is undergoing a worldwide resurgence. The majority of studies of this pathogen are conducted with laboratory-adapted strains which may not be representative of the species as a whole. Biofilm formation by B. pertussis plays an important role in pathogenesis. We conducted a side-by-side comparison of the biofilm-forming abilities of the prototype laboratory strains and the currently circulating isolates from two countries with different vaccination programs. Compared to the reference strain, all strains examined herein formed biofilms at high levels. Biofilm structural analyses revealed country-specific differences, with strains from the United States forming more structured biofilms. Bacterial hyperaggregation and reciprocal expression of biofilm-promoting and -inhibitory factors were observed in clinical isolates. An association of increased biofilm formation with augmented epithelial cell adhesion and higher levels of bacterial colonization in the mouse nose and trachea was detected. To our knowledge, this work links for the first time increased biofilm formation in bacteria with a colonization advantage in an animal model. We propose that the enhanced biofilm-forming capacity of currently circulating strains contributes to their persistence, transmission, and continued circulation.
Collapse
|
33
|
Murch AL, Skipp PJ, Roach PL, Oyston PCF. Whole genome transcriptomics reveals global effects including up-regulation of Francisella pathogenicity island gene expression during active stringent response in the highly virulent Francisella tularensis subsp. tularensis SCHU S4. MICROBIOLOGY-SGM 2017; 163:1664-1679. [PMID: 29034854 PMCID: PMC5845702 DOI: 10.1099/mic.0.000550] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
During conditions of nutrient limitation bacteria undergo a series of global gene expression changes to survive conditions of amino acid and fatty acid starvation. Rapid reallocation of cellular resources is brought about by gene expression changes coordinated by the signalling nucleotides' guanosine tetraphosphate or pentaphosphate, collectively termed (p)ppGpp and is known as the stringent response. The stringent response has been implicated in bacterial virulence, with elevated (p)ppGpp levels being associated with increased virulence gene expression. This has been observed in the highly pathogenic Francisella tularensis sub spp. tularensis SCHU S4, the causative agent of tularaemia. Here, we aimed to artificially induce the stringent response by culturing F. tularensis in the presence of the amino acid analogue l-serine hydroxamate. Serine hydroxamate competitively inhibits tRNAser aminoacylation, causing an accumulation of uncharged tRNA. The uncharged tRNA enters the A site on the translating bacterial ribosome and causes ribosome stalling, in turn stimulating the production of (p)ppGpp and activation of the stringent response. Using the essential virulence gene iglC, which is encoded on the Francisella pathogenicity island (FPI) as a marker of active stringent response, we optimized the culture conditions required for the investigation of virulence gene expression under conditions of nutrient limitation. We subsequently used whole genome RNA-seq to show how F. tularensis alters gene expression on a global scale during active stringent response. Key findings included up-regulation of genes involved in virulence, stress responses and metabolism, and down-regulation of genes involved in metabolite transport and cell division. F. tularensis is a highly virulent intracellular pathogen capable of causing debilitating or fatal disease at extremely low infectious doses. However, virulence mechanisms are still poorly understood. The stringent response is widely recognized as a diverse and complex bacterial stress response implicated in virulence. This work describes the global gene expression profile of F. tularensis SCHU S4 under active stringent response for the first time. Herein we provide evidence for an association of active stringent response with FPI virulence gene expression. Our results further the understanding of the molecular basis of virulence and regulation thereof in F. tularensis. These results also support research into genes involved in (p)ppGpp production and polyphosphate biosynthesis and their applicability as targets for novel antimicrobials.
Collapse
Affiliation(s)
- Amber L Murch
- CBR Division, Defence Science and Technology Laboratory, Salisbury, UK
| | - Paul J Skipp
- School of Chemistry, University of Southampton, Southampton, UK
| | - Peter L Roach
- School of Chemistry, University of Southampton, Southampton, UK
| | - Petra C F Oyston
- CBR Division, Defence Science and Technology Laboratory, Salisbury, UK
| |
Collapse
|
34
|
Mycobacterium tuberculosis PhoY Proteins Promote Persister Formation by Mediating Pst/SenX3-RegX3 Phosphate Sensing. mBio 2017; 8:mBio.00494-17. [PMID: 28698272 PMCID: PMC5513712 DOI: 10.1128/mbio.00494-17] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The Mycobacterium tuberculosis phosphate-specific transport (Pst) system controls gene expression in response to phosphate availability by inhibiting the activation of the SenX3-RegX3 two-component system under phosphate-rich conditions, but the mechanism of communication between these systems is unknown. In Escherichia coli, inhibition of the two-component system PhoR-PhoB under phosphate-rich conditions requires both the Pst system and PhoU, a putative adaptor protein. E. coli PhoU is also involved in the formation of persisters, a subpopulation of phenotypically antibiotic-tolerant bacteria. M. tuberculosis encodes two PhoU orthologs, PhoY1 and PhoY2. We generated phoY single- and double-deletion mutants and examined the expression of RegX3-regulated genes by quantitative reverse transcription-PCR (qRT-PCR). Gene expression was increased only in the ΔphoY1 ΔphoY2 double mutant and could be restored to the wild-type level by complementation with either phoY1 or phoY2 or by deletion of regX3 These data suggest that the PhoY proteins function redundantly to inhibit SenX3-RegX3 activation. We analyzed the frequencies of antibiotic-tolerant persister variants in the phoY mutants using several antibiotic combinations. Persister frequency was decreased at least 40-fold in the ΔphoY1 ΔphoY2 mutant compared to the frequency in the wild type, and this phenotype was RegX3 dependent. A ΔpstA1 mutant lacking a Pst system transmembrane component exhibited a similar RegX3-dependent decrease in persister frequency. In aerosol-infected mice, the ΔphoY1 ΔphoY2 and ΔpstA1 mutants were more susceptible to treatment with rifampin but not isoniazid. Our data demonstrate that disrupting phosphate sensing mediated by the PhoY proteins and the Pst system enhances the susceptibility of M. tuberculosis to antibiotics both in vitro and during infection.IMPORTANCE Persister variants, subpopulations of bacteria that are phenotypically antibiotic tolerant, contribute to the lengthy treatment times required to cure Mycobacterium tuberculosis infection, but the molecular mechanisms governing their formation and maintenance are poorly characterized. Here, we demonstrate that a phosphate-sensing signal transduction system, comprising the Pst phosphate transporter, the two-component system SenX3-RegX3, and functionally redundant PhoY proteins that mediate signaling between Pst and SenX3-RegX3, influences persister formation. Activation of RegX3 by deletion of the phoY genes or a Pst system component resulted in decreased persister formation in vitro Activated RegX3 also limited persister formation during growth under phosphate-limiting conditions. Importantly, increased susceptibility to the front-line drug rifampin was also observed in a mouse infection model. Thus, the M. tuberculosis phosphate-sensing signal transduction system contributes to antibiotic tolerance and is a potential target for the development of novel therapeutics that may shorten the duration of tuberculosis treatment.
Collapse
|
35
|
Kumar A, Gangaiah D, Torrelles JB, Rajashekara G. Polyphosphate and associated enzymes as global regulators of stress response and virulence in Campylobacter jejuni. World J Gastroenterol 2016; 22:7402-7414. [PMID: 27672264 PMCID: PMC5011657 DOI: 10.3748/wjg.v22.i33.7402] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2016] [Revised: 06/03/2016] [Accepted: 07/21/2016] [Indexed: 02/06/2023] Open
Abstract
Campylobacter jejuni (C. jejuni), a Gram-negative microaerophilic bacterium, is a predominant cause of bacterial foodborne gastroenteritis in humans worldwide. Despite its importance as a major foodborne pathogen, our understanding of the molecular mechanisms underlying C. jejuni stress survival and pathogenesis is limited. Inorganic polyphosphate (poly P) has been shown to play significant roles in bacterial resistance to stress and virulence in many pathogenic bacteria. C. jejuni contains the complete repertoire of enzymes required for poly P metabolism. Recent work in our laboratory and others have demonstrated that poly P controls a plethora of C. jejuni properties that impact its ability to survive in the environment as well as to colonize/infect mammalian hosts. This review article summarizes the current literature on the role of poly P in C. jejuni stress survival and virulence and discusses on how poly P-related enzymes can be exploited for therapeutic/prevention purposes. Additionally, the review article identifies potential areas for future investigation that would enhance our understanding of the role of poly P in C. jejuni and other bacteria, which ultimately would facilitate design of effective therapeutic/preventive strategies to reduce not only the burden of C. jejuni-caused foodborne infections but also of other bacterial infections in humans.
Collapse
|
36
|
Inorganic polyphosphate in the microbial world. Emerging roles for a multifaceted biopolymer. World J Microbiol Biotechnol 2016; 32:27. [DOI: 10.1007/s11274-015-1983-2] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 11/05/2015] [Indexed: 10/22/2022]
|
37
|
The response of foodborne pathogens to osmotic and desiccation stresses in the food chain. Int J Food Microbiol 2016; 221:37-53. [PMID: 26803272 DOI: 10.1016/j.ijfoodmicro.2015.12.014] [Citation(s) in RCA: 124] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 12/22/2015] [Accepted: 12/30/2015] [Indexed: 12/24/2022]
Abstract
In combination with other strategies, hyperosmolarity and desiccation are frequently used by the food processing industry as a means to prevent bacterial proliferation, and particularly that of foodborne pathogens, in food products. However, it is increasingly observed that bacteria, including human pathogens, encode mechanisms to survive and withstand these stresses. This review provides an overview of the mechanisms employed by Salmonella spp., Shiga toxin producing E. coli, Cronobacter spp., Listeria monocytogenes and Campylobacter spp. to tolerate osmotic and desiccation stresses and identifies gaps in knowledge which need to be addressed to ensure the safety of low water activity and desiccated food products.
Collapse
|
38
|
Polyphosphate kinases modulate Campylobacter jejuni outer membrane constituents and alter its capacity to invade and survive in intestinal epithelial cells in vitro. Emerg Microbes Infect 2015; 4:e77. [PMID: 26714783 PMCID: PMC4715166 DOI: 10.1038/emi.2015.77] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 09/28/2015] [Accepted: 10/01/2015] [Indexed: 12/12/2022]
Abstract
Campylobacter jejuni is the most prevalent cause of bacterial gastroenteritis worldwide. Polyphosphate kinases 1 and 2 (PPK1 and PPK2) regulate several cellular processes, including the biosynthesis of the bacterial cell wall. Despite their importance, whether PPK1 and PPK2 modulate the composition of C. jejuni outer membrane constituents (OMCs) and consequently impact its interaction with host cells remains unknown. Our comparative analysis between C. jejuni wild type, Δppk1, and Δppk2 strains showed qualitative and quantitative differences in the total OMC composition among these strains. Importantly, these OMC variations observed on the C. jejuni polyphosphate kinase mutants are directly related to their capacity to invade, survive, and alter the immune response of intestinal epithelial cells in vitro. Specifically, sub-fractionation of the C. jejuni OMC indicated that OMC proteins are uniquely associated with bacterial invasion, whereas C. jejuni OMC proteins, lipids, and lipoglycans are all associated with C. jejuni intracellular survival. This study provides new insights regarding the function of polyphosphate kinases and their role in C. jejuni infection.
Collapse
|
39
|
Biochemical and structural characterization of polyphosphate kinase 2 from the intracellular pathogen Francisella tularensis. Biosci Rep 2015; 36:e00294. [PMID: 26582818 PMCID: PMC4748334 DOI: 10.1042/bsr20150203] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 10/28/2015] [Indexed: 01/17/2023] Open
Abstract
The polyphosphate kinase 2 (PPK2) from the intracellular pathogen Francisella tularensis has been characterized by a range of biochemical methods and X-ray crystallography. The antibiotic sensitivity of a deletion mutant lacking the gene encoding PPK2 is also reported. The metabolism of polyphosphate is important for the virulence of a wide range of pathogenic bacteria and the enzymes of polyphosphate metabolism have been proposed as an anti-bacterial target. In the intracellular pathogen Francisella tularensis, the product of the gene FTT1564 has been identified as a polyphosphate kinase from the polyphosphate kinase 2 (PPK2) family. The isogenic deletion mutant was defective for intracellular growth in macrophages and was attenuated in mice, indicating an important role for polyphosphate in the virulence of Francisella. Herein, we report the biochemical and structural characterization of F. tularensis polyphosphate kinase (FtPPK2) with a view to characterizing the enzyme as a novel target for inhibitors. Using an HPLC-based activity assay, the substrate specificity of FtPPK2 was found to include purine but not pyrimidine nts. The activity was also measured using 31P-NMR. FtPPK2 has been crystallized and the structure determined to 2.23 Å (1 Å=0.1 nm) resolution. The structure consists of a six-stranded parallel β-sheet surrounded by 12 α-helices, with a high degree of similarity to other members of the PPK2 family and the thymidylate kinase superfamily. Residues proposed to be important for substrate binding and catalysis have been identified in the structure, including a lid-loop and the conserved Walker A and B motifs. The ΔFTT1564 strain showed significantly increased sensitivity to a range of antibiotics in a manner independent of the mode of action of the antibiotic. This combination of biochemical, structural and microbiological data provide a sound foundation for future studies targeting the development of PPK2 small molecule inhibitors.
Collapse
|
40
|
Duarte A, Alves AC, Ferreira S, Silva F, Domingues FC. Resveratrol inclusion complexes: Antibacterial and anti-biofilm activity against Campylobacter spp. and Arcobacter butzleri. Food Res Int 2015. [DOI: 10.1016/j.foodres.2015.05.047] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
41
|
High-Frequency Variation of Purine Biosynthesis Genes Is a Mechanism of Success in Campylobacter jejuni. mBio 2015; 6:e00612-15. [PMID: 26419875 PMCID: PMC4611032 DOI: 10.1128/mbio.00612-15] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
UNLABELLED Phenotypic variation is prevalent in the zoonotic pathogen Campylobacter jejuni, the leading agent of enterocolitis in the developed world. Heterogeneity enhances the survival and adaptive malleability of bacterial populations because variable phenotypes may allow some cells to be protected against future stress. Exposure to hyperosmotic stress previously revealed prevalent differences in growth between C. jejuni strain 81-176 colonies due to resistant or sensitive phenotypes, and these isolated colonies continued to produce progeny with differential phenotypes. In this study, whole-genome sequencing of isolated colonies identified allelic variants of two purine biosynthesis genes, purF and apt, encoding phosphoribosyltransferases that utilize a shared substrate. Genetic analyses determined that purF was essential for fitness, while apt was critical. Traditional and high-depth amplicon-sequencing analyses confirmed extensive intrapopulation genetic variation of purF and apt that resulted in viable strains bearing alleles with in-frame insertion duplications, deletions, or missense polymorphisms. Different purF and apt alleles were associated with various stress survival capabilities under several niche-relevant conditions and contributed to differential intracellular survival in an epithelial cell infection model. Amplicon sequencing revealed that intracellular survival selected for stress-fit purF and apt alleles, as did exposure to oxygen and hyperosmotic stress. Putative protein recognition direct repeat sequences were identified in purF and apt, and a DNA-protein affinity screen captured a predicted exonuclease that promoted the global spontaneous mutation rate. This work illustrates the adaptive properties of high-frequency genetic variation in two housekeeping genes, which influences C. jejuni survival under stress and promotes its success as a pathogen. IMPORTANCE C. jejuni is an important cause of bacterial diarrheal illness. Bacterial populations have many strategies for stress survival, but phenotypic variation due to genetic diversity has a powerful advantage: no matter how swift the change in environment, a fraction of the population already expresses the survival trait. Nonclonality is thus increasingly viewed as a mechanism of population success. Our previous work identified prominent resistant/sensitive colonial variation in C. jejuni bacteria in response to hyperosmotic stress; in the work presented here, we attribute that to high-frequency genetic variation in two purine biosynthesis genes, purF and apt. We demonstrated selective pressure for nonlethal mutant alleles of both genes, showed that single-cell variants had the capacity to give rise to diverse purF and apt populations, and determined that stress exposure selected for desirable alleles. Thus, a novel C. jejuni adaptive strategy was identified, which was, unusually, reliant on prevalent genetic variation in two housekeeping genes.
Collapse
|
42
|
Turonova H, Briandet R, Rodrigues R, Hernould M, Hayek N, Stintzi A, Pazlarova J, Tresse O. Biofilm spatial organization by the emerging pathogen Campylobacter jejuni: comparison between NCTC 11168 and 81-176 strains under microaerobic and oxygen-enriched conditions. Front Microbiol 2015. [PMID: 26217332 PMCID: PMC4499754 DOI: 10.3389/fmicb.2015.00709] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
During the last years, Campylobacter has emerged as the leading cause of bacterial foodborne infections in developed countries. Described as an obligate microaerophile, Campylobacter has puzzled scientists by surviving a wide range of environmental oxidative stresses on foods farm to retail, and thereafter intestinal transit and oxidative damage from macrophages to cause human infection. In this study, confocal laser scanning microscopy (CLSM) was used to explore the biofilm development of two well-described Campylobacter jejuni strains (NCTC 11168 and 81-176) prior to or during cultivation under oxygen-enriched conditions. Quantitative and qualitative appraisal indicated that C. jejuni formed finger-like biofilm structures with an open ultrastructure for 81-176 and a multilayer-like structure for NCTC 11168 under microaerobic conditions (MAC). The presence of motile cells within the biofilm confirmed the maturation of the C. jejuni 81-176 biofilm. Acclimation of cells to oxygen-enriched conditions led to significant enhancement of biofilm formation during the early stages of the process. Exposure to these conditions during biofilm cultivation induced an even greater biofilm development for both strains, indicating that oxygen demand for biofilm formation is higher than for planktonic growth counterparts. Overexpression of cosR in the poorer biofilm-forming strain, NCTC 11168, enhanced biofilm development dramatically by promoting an open ultrastructure similar to that observed for 81-176. Consequently, the regulator CosR is likely to be a key protein in the maturation of C. jejuni biofilm, although it is not linked to oxygen stimulation. These unexpected data advocate challenging studies by reconsidering the paradigm of fastidious requirements for C. jejuni growth when various subpopulations (from quiescent to motile cells) coexist in biofilms. These findings constitute a clear example of a survival strategy used by this emerging human pathogen.
Collapse
Affiliation(s)
- Hana Turonova
- SECALIM UMR1014, Institut National de la Recherche Agronomique Nantes, France ; LUNAM Université, Oniris, Université de Nantes Nantes, France ; Department of Biochemistry and Microbiology, Faculty of Food and Biochemical Technology, University of Chemistry and Technology Prague, Czech Republic
| | - Romain Briandet
- MICALIS UMR1319, Institut National de la Recherche Agronomique Massy, France
| | - Ramila Rodrigues
- SECALIM UMR1014, Institut National de la Recherche Agronomique Nantes, France ; LUNAM Université, Oniris, Université de Nantes Nantes, France
| | | | - Nabil Hayek
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa Ottawa, ON, Canada
| | - Alain Stintzi
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa Ottawa, ON, Canada
| | - Jarmila Pazlarova
- Department of Biochemistry and Microbiology, Faculty of Food and Biochemical Technology, University of Chemistry and Technology Prague, Czech Republic
| | - Odile Tresse
- SECALIM UMR1014, Institut National de la Recherche Agronomique Nantes, France ; LUNAM Université, Oniris, Université de Nantes Nantes, France
| |
Collapse
|
43
|
Drozd M, Chandrashekhar K, Rajashekara G. Polyphosphate-mediated modulation of Campylobacter jejuni biofilm growth and stability. Virulence 2015; 5:680-90. [PMID: 25127528 DOI: 10.4161/viru.34348] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Biofilms increase C. jejuni's resilience to detergents, antibiotics, and environmental stressors. In these investigations, we studied the modulation of biofilm in response to phosphate related stressors. We found that the deletion of ppk1, phoX, and ppk2 (polyphosphate associated [poly P] genes) in C. jejuni modulated different stages of biofilm formation such as attached microcolonies, air-liquid biofilms, and biofilm shedding. Additionally, inorganic phosphate also modulated attached microcolonies, air-liquid biofilms, and biofilm shedding both independently of and additively in the poly P associated mutants. Furthermore, we observed that these different biofilm stages were affected by biofilm age: for example, the adherent microcolonies were maximum on day 2, while biofilm growth at the air-liquid interface and shedding was highest on day 3. Also, we observed altered calcofluor white reactive polysaccharides in poly P-associated mutants, as well as increased secretion of autoinducer-2 (AI-2) quorum sensing molecules in the ∆ppk2 mutant. Further, the polysaccharide and flagellar biosynthesis genes, that are associated with biofilm formation, were altered in these poly P-associated mutants. We conclude that the phosphate limiting condition modulates C. jejuni biofilm formation.
Collapse
Affiliation(s)
- Mary Drozd
- Food Animal Health Research Program; Ohio Agricultural Research and Development Center; Department of Veterinary Preventive Medicine; The Ohio State University; Wooster, OH USA
| | - Kshipra Chandrashekhar
- Food Animal Health Research Program; Ohio Agricultural Research and Development Center; Department of Veterinary Preventive Medicine; The Ohio State University; Wooster, OH USA
| | - Gireesh Rajashekara
- Food Animal Health Research Program; Ohio Agricultural Research and Development Center; Department of Veterinary Preventive Medicine; The Ohio State University; Wooster, OH USA
| |
Collapse
|
44
|
Vieira A, Seddon AM, Karlyshev AV. Campylobacter-Acanthamoeba interactions. MICROBIOLOGY-SGM 2015; 161:933-947. [PMID: 25757600 DOI: 10.1099/mic.0.000075] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 03/09/2015] [Indexed: 02/02/2023]
Abstract
Campylobacter jejuni is a foodborne pathogen recognized as the major cause of human bacterial enteritis. Undercooked poultry products and contaminated water are considered as the most important sources of infection. Some studies suggest transmission and survival of this bacterial pathogen may be assisted by the free-living protozoa Acanthamoeba. The latter is known to play the role of a host for various pathogenic bacteria, protecting them from harsh environmental conditions. Importantly, there is a similarity between the mechanisms of bacterial survival within amoebae and macrophages, making the former a convenient tool for the investigation of the survival of pathogenic bacteria in the environment. However, the molecular mechanisms involved in the interaction between Campylobacter and Acanthamoeba are not well understood. Whilst some studies suggest the ability of C. jejuni to survive within the protozoa, the other reports support an extracellular mode of survival only. In this review, we focus on the studies investigating the interaction between Campylobacter and Acanthamoeba, address some reasons for the contradictory results, and discuss possible implications of these results for epidemiology. Additionally, as the molecular mechanisms involved remain unknown, we also suggest possible factors that may be involved in this process. Deciphering the molecular mechanisms of pathogen-protozoa interaction will assist in a better understanding of Campylobacter lifestyle and in the development of novel antibacterial drugs.
Collapse
Affiliation(s)
- Ana Vieira
- Faculty of Science, Engineering and Computing, Kingston University, Penrhyn Road, Kingston upon Thames, Surrey KT1 2EE, UK
| | - Alan M Seddon
- Faculty of Science, Engineering and Computing, Kingston University, Penrhyn Road, Kingston upon Thames, Surrey KT1 2EE, UK
| | - Andrey V Karlyshev
- Faculty of Science, Engineering and Computing, Kingston University, Penrhyn Road, Kingston upon Thames, Surrey KT1 2EE, UK
| |
Collapse
|
45
|
Hofreuter D. Defining the metabolic requirements for the growth and colonization capacity of Campylobacter jejuni. Front Cell Infect Microbiol 2014; 4:137. [PMID: 25325018 PMCID: PMC4178425 DOI: 10.3389/fcimb.2014.00137] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 09/11/2014] [Indexed: 01/27/2023] Open
Abstract
During the last decade Campylobacter jejuni has been recognized as the leading cause of bacterial gastroenteritis worldwide. This facultative intracellular pathogen is a member of the Epsilonproteobacteria and requires microaerobic atmosphere and nutrient rich media for efficient proliferation in vitro. Its catabolic capacity is highly restricted in contrast to Salmonella Typhimurium and other enteropathogenic bacteria because several common pathways for carbohydrate utilization are either missing or incomplete. Despite these metabolic limitations, C. jejuni efficiently colonizes various animal hosts as a commensal intestinal inhabitant. Moreover, C. jejuni is tremendously successful in competing with the human intestinal microbiota; an infectious dose of few hundreds bacteria is sufficient to overcome the colonization resistance of humans and can lead to campylobacteriosis. Besides the importance and clear clinical manifestation of this disease, the pathogenesis mechanisms of C. jejuni infections are still poorly understood. In recent years comparative genome sequence, transcriptome and metabolome analyses as well as mutagenesis studies combined with animal infection models have provided a new understanding of how the specific metabolic capacity of C. jejuni drives its persistence in the intestinal habitat of various hosts. Furthermore, new insights into the metabolic requirements that support the intracellular survival of C. jejuni were obtained. Because C. jejuni harbors distinct properties in establishing an infection in comparison to pathogenic Enterobacteriaceae, it represents an excellent organism for elucidating new aspects of the dynamic interaction and metabolic cross talk between a bacterial pathogen, the microbiota and the host.
Collapse
Affiliation(s)
- Dirk Hofreuter
- Hannover Medical School, Institute for Medical Microbiology and Hospital Epidemiology Hannover, Germany
| |
Collapse
|
46
|
Flagella-mediated adhesion and extracellular DNA release contribute to biofilm formation and stress tolerance of Campylobacter jejuni. PLoS One 2014; 9:e106063. [PMID: 25166748 PMCID: PMC4148357 DOI: 10.1371/journal.pone.0106063] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Accepted: 07/31/2014] [Indexed: 11/19/2022] Open
Abstract
Campylobacter jejuni is a leading cause of foodbourne gastroenteritis, despite fragile behaviour under standard laboratory conditions. In the environment, C. jejuni may survive within biofilms, which can impart resident bacteria with enhanced stress tolerance compared to their planktonic counterparts. While C. jejuni forms biofilms in vitro and in the wild, it had not been confirmed that this lifestyle confers stress tolerance. Moreover, little is understood about molecular mechanisms of biofilm formation in this pathogen. We previously found that a ΔcprS mutant, which carries a deletion in the sensor kinase of the CprRS two-component system, forms enhanced biofilms. Biofilms were also enhanced by the bile salt deoxycholate and contained extracellular DNA. Through more in-depth analysis of ΔcprS and WT under conditions that promote or inhibit biofilms, we sought to further define this lifestyle for C. jejuni. Epistasis experiments with ΔcprS and flagellar mutations (ΔflhA, ΔpflA) suggested that initiation is mediated by flagellum-mediated adherence, a process which was kinetically enhanced by motility. Lysis was also observed, especially under biofilm-enhancing conditions. Microscopy suggested adherence was followed by release of eDNA, which was required for biofilm maturation. Importantly, inhibiting biofilm formation by removal of eDNA with DNase decreased stress tolerance. This work suggests the biofilm lifestyle provides C. jejuni with resilience that has not been apparent from observation of planktonic bacteria during routine laboratory culture, and provides a framework for subsequent molecular studies of C. jejuni biofilms.
Collapse
|
47
|
Müller A, Beeby M, McDowall AW, Chow J, Jensen GJ, Clemons WM. Ultrastructure and complex polar architecture of the human pathogen Campylobacter jejuni. Microbiologyopen 2014; 3:702-10. [PMID: 25065852 PMCID: PMC4234261 DOI: 10.1002/mbo3.200] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 06/17/2014] [Accepted: 06/27/2014] [Indexed: 12/12/2022] Open
Abstract
Campylobacter jejuni is one of the most successful food-borne human pathogens. Here we use electron cryotomography to explore the ultrastructure of C. jejuni cells in logarithmically growing cultures. This provides the first look at this pathogen in a near-native state at macromolecular resolution (~5 nm). We find a surprisingly complex polar architecture that includes ribosome exclusion zones, polyphosphate storage granules, extensive collar-shaped chemoreceptor arrays, and elaborate flagellar motors.
Collapse
Affiliation(s)
- Axel Müller
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, California, 91125
| | | | | | | | | | | |
Collapse
|
48
|
Bronowski C, James CE, Winstanley C. Role of environmental survival in transmission of Campylobacter jejuni. FEMS Microbiol Lett 2014; 356:8-19. [PMID: 24888326 DOI: 10.1111/1574-6968.12488] [Citation(s) in RCA: 115] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Revised: 05/20/2014] [Accepted: 05/24/2014] [Indexed: 11/29/2022] Open
Abstract
Campylobacter species are the most common cause of bacterial gastroenteritis, with C. jejuni responsible for the majority of these cases. Although it is clear that livestock, and particularly poultry, are the most common source, it is likely that the natural environment (soil and water) plays a key role in transmission, either directly to humans or indirectly via farm animals. It has been shown using multilocus sequence typing that some clonal complexes (such as ST-45) are more frequently isolated from environmental sources such as water, suggesting that strains vary in their ability to survive in the environment. Although C. jejuni are fastidious microaerophiles generally unable to grow in atmospheric levels of oxygen, C. jejuni can adapt to survival in the environment, exhibiting aerotolerance and starvation survival. Biofilm formation, the viable but nonculturable state, and interactions with other microorganisms can all contribute to survival outside the host. By exploiting high-throughput technologies such as genome sequencing and RNA Seq, we are well placed to decipher the mechanisms underlying the variations in survival between strains in environments such as soil and water and to better understand the role of environmental persistence in the transmission of C. jejuni directly or indirectly to humans.
Collapse
Affiliation(s)
- Christina Bronowski
- Institute of Infection and Global Health, University of Liverpool, Liverpool, UK
| | | | | |
Collapse
|
49
|
Defects in phosphate acquisition and storage influence virulence of Cryptococcus neoformans. Infect Immun 2014; 82:2697-712. [PMID: 24711572 DOI: 10.1128/iai.01607-14] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Nutrient acquisition and sensing are critical aspects of microbial pathogenesis. Previous transcriptional profiling indicated that the fungal pathogen Cryptococcus neoformans, which causes meningoencephalitis in immunocompromised individuals, encounters phosphate limitation during proliferation in phagocytic cells. We therefore tested the hypothesis that phosphate acquisition and polyphosphate metabolism are important for cryptococcal virulence. Deletion of the high-affinity uptake system interfered with growth on low-phosphate medium, perturbed the formation of virulence factors (capsule and melanin), reduced survival in macrophages, and attenuated virulence in a mouse model of cryptococcosis. Additionally, analysis of nutrient sensing functions for C. neoformans revealed regulatory connections between phosphate acquisition and storage and the iron regulator Cir1, cyclic AMP (cAMP)-dependent protein kinase A (PKA), and the calcium-calmodulin-activated protein phosphatase calcineurin. Deletion of the VTC4 gene encoding a polyphosphate polymerase blocked the ability of C. neoformans to produce polyphosphate. The vtc4 mutant behaved like the wild-type strain in interactions with macrophages and in the mouse infection model. However, the fungal load in the lungs was significantly increased in mice infected with vtc4 deletion mutants. In addition, the mutant was impaired in the ability to trigger blood coagulation in vitro, a trait associated with polyphosphate. Overall, this study reveals that phosphate uptake in C. neoformans is critical for virulence and that its regulation is integrated with key signaling pathways for nutrient sensing.
Collapse
|
50
|
Affiliation(s)
- Byeonghwa Jeon
- School of Public Health; University of Alberta; Edmonton, AB Canada
| |
Collapse
|