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MBio Mar 2020The posttranslational Ca-dependent "clip-and-link" activity of large epeat-in-oin (RTX) proteins starts by Ca-dependent structural rearrangement of a highly conserved...
The posttranslational Ca-dependent "clip-and-link" activity of large epeat-in-oin (RTX) proteins starts by Ca-dependent structural rearrangement of a highly conserved self-processing module (SPM). Subsequently, an internal aspartate-proline (Asp-Pro) peptide bond at the N-terminal end of SPM breaks, and the liberated C-terminal aspartyl residue can react with a free ε-amino group of an adjacent lysine residue to form a new isopeptide bond. Here, we report a solution structure of the calcium-loaded SPM (Ca-SPM) derived from the FrpC protein of The Ca-SPM structure defines a unique protein architecture and provides structural insight into the autocatalytic cleavage of the Asp-Pro peptide bond through a "twisted-amide" activation. Furthermore, in-frame deletion of the SPM domain from the ApxIVA protein of attenuated the virulence of this porcine pathogen in a pig respiratory challenge model. We hypothesize that the Ca-dependent clip-and-link activity represents an unconventional strategy for Gram-negative pathogens to adhere to the host target cell surface. The Ca-dependent clip-and-link activity of large repeat-in-toxin (RTX) proteins is an exceptional posttranslational process in which an internal domain called a self-processing module (SPM) mediates Ca-dependent processing of a highly specific aspartate-proline (Asp-Pro) peptide bond and covalent linkage of the released aspartyl to an adjacent lysine residue through an isopeptide bond. Here, we report the solution structures of the Ca-loaded SPM (Ca-SPM) defining the mechanism of the autocatalytic cleavage of the Asp414-Pro415 peptide bond of the FrpC exoprotein. Moreover, deletion of the SPM domain in the ApxIVA protein, the FrpC homolog of , resulted in attenuation of virulence of the bacterium in a pig infection model, indicating that the Ca-dependent clip-and-link activity plays a role in the virulence of Gram-negative pathogens.
Topics: Actinobacillus Infections; Actinobacillus pleuropneumoniae; Animals; Bacterial Proteins; Bacterial Toxins; Calcium; Membrane Proteins; Neisseria meningitidis; Protein Processing, Post-Translational; Swine; Virulence
PubMed: 32184239
DOI: 10.1128/mBio.00226-20 -
Nature Communications Apr 2020Succinic acid (SA), a dicarboxylic acid of industrial importance, can be efficiently produced by metabolically engineered Mannheimia succiniciproducens. Malate...
Succinic acid (SA), a dicarboxylic acid of industrial importance, can be efficiently produced by metabolically engineered Mannheimia succiniciproducens. Malate dehydrogenase (MDH) is one of the key enzymes for SA production, but has not been well characterized. Here we report biochemical and structural analyses of various MDHs and development of hyper-SA producing M. succiniciproducens by introducing the best MDH. Corynebacterium glutamicum MDH (CgMDH) shows the highest specific activity and least substrate inhibition, whereas M. succiniciproducens MDH (MsMDH) shows low specific activity at physiological pH and strong uncompetitive inhibition toward oxaloacetate (ki of 67.4 and 588.9 μM for MsMDH and CgMDH, respectively). Structural comparison of the two MDHs reveals a key residue influencing the specific activity and susceptibility to substrate inhibition. A high-inoculum fed-batch fermentation of the final strain expressing cgmdh produces 134.25 g L of SA with the maximum productivity of 21.3 g L h, demonstrating the importance of enzyme optimization in strain development.
Topics: Bacterial Proteins; Bioreactors; Corynebacterium glutamicum; Fermentation; Kinetics; Malate Dehydrogenase; Metabolic Engineering; Oxaloacetic Acid; Pasteurellaceae; Protein Conformation; Recombinant Proteins; Substrate Specificity; Succinic Acid
PubMed: 32327663
DOI: 10.1038/s41467-020-15839-z -
PloS One 2023Respiratory disease is responsible for dramatic population declines in bighorn sheep (Ovis canadensis), and respiratory pathogen diagnostics contribute to the management...
Assessing shared respiratory pathogens between domestic (Ovis aries) and bighorn (Ovis canadensis) sheep; methods for multiplex PCR, amplicon sequencing, and bioinformatics to characterize respiratory flora.
Respiratory disease is responsible for dramatic population declines in bighorn sheep (Ovis canadensis), and respiratory pathogen diagnostics contribute to the management of bighorn populations. To create a comprehensive and consistent approach to bighorn sheep respiratory diagnostics, we created a culture-independent assay to detect and strain type Mannheimia haemolytica, Bibersteinia trehalosi, Pasteurella multocida, and Mycoplasma ovipneumoniae. The assay also detects and characterizes the Pasteurellaceae leukotoxin A gene, and broadly assesses the bacterial composition of each sample based on 16S rRNA sequences. The assay is based on a three-step approach: 1) Multiplex PCR to amplify targets including eight loci for each bacterial species, the Pasteurellaceae lktA gene, and the 16S rRNA gene 2) Library preparation, barcoding, and short-read Illumina sequencing to determine the genetic sequences of each target, and 3) Bioinformatics in the form of automated software to analyze genetic sequences. The assay was designed to assess shared pathogens between domestic and bighorn sheep, but could be useful for many applications in bighorn sheep respiratory disease research and management.
Topics: Animals; Sheep; Sheep, Bighorn; Sheep, Domestic; Multiplex Polymerase Chain Reaction; RNA, Ribosomal, 16S; Sheep Diseases; Mannheimia haemolytica; Respiratory Tract Diseases; Computational Biology
PubMed: 37856492
DOI: 10.1371/journal.pone.0293062 -
Medicina 2024Brain abscess is a focal suppurative process produced in most cases by bacterial agents. Aggregatibacter aphrophilus is a gram-negative bacteria belonging to the HACEK...
Brain abscess is a focal suppurative process produced in most cases by bacterial agents. Aggregatibacter aphrophilus is a gram-negative bacteria belonging to the HACEK group, which causes infective endocarditis, liver abscesses, among others. Brain abscesses secondary to this germ are rare and, in most cases, it is associated with contact with pets, poor dental hygiene or dental procedures. Treatment consists of drainage of the abscess (greater than 2.5 cm) combined with antibiotic therapy, ideally beta-lactams. The case of a 64-year-old male patient with no relevant history is here presented. He was admitted to the emergency service due to headache, hemianopsia of a week's duration and later tonic-clonic seizures, in whom imaging studies and culture of a brain lesion subsequently revealed a brain abscess due to A. aphrophilus. This case aims to illustrate about the rarity of this infection, because A. aphrophilus is a normal part of the oropharyngeal flora and respiratory tract, in which it rarely causes invasive bacteremia.
Topics: Brain Abscess; Humans; Male; Aggregatibacter aphrophilus; Middle Aged; Pasteurellaceae Infections; Anti-Bacterial Agents; Drainage
PubMed: 38683524
DOI: No ID Found -
Medicine Jan 2016Actinobacillus actinomycetemcomitans infection is a rare and easily misdiagnosed ocular disease. In this article, the authors report a chronic, purulent, and... (Review)
Review
Actinobacillus actinomycetemcomitans infection is a rare and easily misdiagnosed ocular disease. In this article, the authors report a chronic, purulent, and difficult-to-treat case of A actinomycetemcomitans keratitis following a glaucoma infiltration surgery.A 56-year-old man with a long-standing history of open-angle glaucoma in both eyes presented with a 12-week history of ocular pain, redness, and blurred vision in his right eye. He underwent a glaucoma infiltration surgery in his right eye 6 months ago. Three months postoperatively, he developed peripheral corneal stromal opacities associated with a white, thin, cystic bleb, and conjunctival injection. These opacities grew despite topical treatment with topical tobramycin, levofloxacin, natamycin, amikacin, and metronidazole eye drops.Multiple corneal scrapings revealed no organisms, and no organisms grew on aerobic, anaerobic, fungal, or mycobacterial cultures. The patient's right eye developed a severe purulent corneal ulcer with a dense hypopyon and required a corneal transplantation. Histopathologic analysis and 16S ribosomalribonucleic acid polymerase chain reaction sequencing revealed A actinomycetemcomitans as the causative organism. Postoperatively, treatment was initiated with topical levofloxacin and cyclosporine, as well as oral levofloxacin and cyclosporine. Graft and host corneal transparency were maintained at the checkup 1 month after surgery.Although it is a rare cause of corneal disease, A actinomycetemcomitans should be suspected in patients with keratitis refractory to topical antibiotic therapy. Delay in diagnosis and appropriate treatment can result in vision loss.
Topics: Aggregatibacter actinomycetemcomitans; Glaucoma Drainage Implants; Glaucoma, Open-Angle; Humans; Keratitis; Male; Middle Aged; Pasteurellaceae Infections
PubMed: 26817919
DOI: 10.1097/MD.0000000000002608 -
Clinical Microbiology and Infection :... Jul 2020To compare the determinants of trimethoprim-sulfamethoxazole resistance with established susceptibility values for fastidious Haemophilus spp., to provide... (Comparative Study)
Comparative Study
OBJECTIVES
To compare the determinants of trimethoprim-sulfamethoxazole resistance with established susceptibility values for fastidious Haemophilus spp., to provide recommendations for optimal trimethoprim-sulfamethoxazole measurement.
METHODS
We collected 50 strains each of Haemophilus influenzae and Haemophilus parainfluenzae at Bellvitge University Hospital. Trimethoprim-sulfamethoxazole susceptibility was tested by microdilution, E-test and disc diffusion using both Mueller-Hinton fastidious (MH-F) medium and Haemophilus test medium (HTM) following EUCAST and CLSI criteria, respectively. Mutations in folA, folP and additional determinants of resistance were identified in whole-genome-sequenced isolates.
RESULTS
Strains presented generally higher rates of trimethoprim-sulfamethoxazole resistance when grown on HTM than on MH-F, independent of the methodology used (average MIC 2.6-fold higher in H. influenzae and 1.2-fold higher in H. parainfluenzae). The main resistance-related determinants were as follows: I95L and F154S/V in folA; 3- and 15-bp insertions and substitutions in folP; acquisition of sul genes; and FolA overproduction potentially linked to mutations in -35 and -10 promoter motifs. Of note, 2 of 19 H. influenzae strains (10.5%) and 9 of 33 H. parainfluenzae strains (27.3%) with mutations and assigned as resistant by microdilution were inaccurately considered susceptible by disc diffusion. This misinterpretation was resolved by raising the clinical resistance breakpoint of the EUCAST guidelines to ≤30 mm.
CONCLUSIONS
Given the routine use of disc diffusion, a significant number of strains could potentially be miscategorized as susceptible to trimethoprim-sulfamethoxazole despite having resistance-related mutations. A simple modification to the current clinical resistance breakpoint given by the EUCAST guideline for MH-F ensures correct interpretation and correlation with the reference standard method of microdilution.
Topics: Anti-Bacterial Agents; Bacterial Proteins; Culture Media; Drug Resistance, Multiple, Bacterial; Haemophilus Infections; Haemophilus influenzae; Haemophilus parainfluenzae; High-Throughput Nucleotide Sequencing; Humans; Microbial Sensitivity Tests; Mutation; Promoter Regions, Genetic; Trimethoprim, Sulfamethoxazole Drug Combination; Whole Genome Sequencing
PubMed: 31811916
DOI: 10.1016/j.cmi.2019.11.022 -
The Journal of Veterinary Medical... Sep 2023Immunostimulants and vaccines are the main means for controlling infectious diseases and searching highly effective and low toxic immunestimulants has always been the...
Immunostimulants and vaccines are the main means for controlling infectious diseases and searching highly effective and low toxic immunestimulants has always been the focus of researchers. The MetchnikowinII (MetII) had been expressed by us and exhibited both antibacterial and antifungal activities, in this study, we evaluated its potential for an adjuvant effect. In chickens, antigen-specific immunoglobulin Gs (IgGs) were increased after MetII adjuvanted vaccination using the Ptfa protein. Compared to group Ptfa + iFA, which was only adjuvanted with incomplete Freund's adjuvant (iFA), the antibody titers of the group Ptfa + iFA + Met20 μg·mL (PFM) and Ptfa + iFA + Propolis (PFP) significantly increased (P<0.05). Likewise, Interleukin-2 (IL-2) and Interferon-γ (IFN-γ) cytokines in group Ptfa + iFA + Met20 μg·mL (PFM) and Ptfa + iFA + Propolis (PFP) were significantly higher than those of the other three experimental groups (P<0.05). The stimulation index (SI) value in chickens of group PFM was significantly higher than that of the other four experimental groups (P<0.05). Chickens that received MetII adjuvanted vaccinations benefitted from higher protection rate (88%) when challenged with Pasteurella multocida (P. multocida), which was significantly higher than those of group PF and PFP (P<0.05). These results suggested that the antimicrobial peptide MetII may play an adjuvant role in the immune response in chickens but need a proper usage, because the higher usage of 40 μg·mL and 60 μg·mL resulted poor effect. Whether MetII could be a potential adjuvant or a biomolecule as part of a complex adjuvant for vaccines needs more experimental evidence, the study still provides an examples for understanding vaccine adjuvants.
Topics: Animals; Pasteurella multocida; Chickens; Propolis; Adjuvants, Immunologic; Antigens; Immunity
PubMed: 37407447
DOI: 10.1292/jvms.22-0579 -
Journal of Dairy Science Mar 2020Respiratory tract infections (bovine respiratory disease) are a major concern in calf rearing. The objective of this study was to identify pathogen-specific risk factors...
Respiratory tract infections (bovine respiratory disease) are a major concern in calf rearing. The objective of this study was to identify pathogen-specific risk factors associated with epidemic respiratory disease in calves. A cross-sectional study was conducted, involving 128 outbreaks (29 dairy, 58 dairy-mixed, and 41 beef) in Belgium (2016-2018). A semiquantitative PCR for 7 respiratory pathogens was done on a pooled nonendoscopic bronchoalveolar lavage sample for each herd. Potential risk factors were collected by questionnaire and derived from the national cattle registration databank. Most outbreaks occurred between October and March, and single and multiple viral infections were detected in 58.6% (75/128) and 13.3% (17/128), respectively. Bovine coronavirus (BCV) was the most frequently isolated virus (38.4%), followed by bovine respiratory syncytial virus (bRSV; 29.4%) and parainfluenzavirus type 3 (PI-3; 8.1%). Mycoplasma bovis, Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni were detected in 33.3, 41.2, 89.1, and 36.4% of the herds, respectively. Specific risk factors for BCV detection were detection of M. haemolytica [odds ratio (OR) = 2.8 (95% confidence interval = 1.1-7.5)], increasing herd size [OR = 1.3 (1.0-1.8) for each increase with 100 animals] and detection of BCV by antigen ELISA on feces in calves in the last year [OR = 3.6 (1.2-11.1)]. A seasonal effect was shown for bRSV only {more in winter compared with autumn [OR = 10.3 (2.8-37.5)]}. Other factors associated with bRSV were PI-3 detection [OR = 13.4 (2.1-86.0)], prevalence of calves with respiratory disease [OR = 1.02 (1.00-1.04) per 1% increase], and number of days with respiratory signs before sampling [OR = 0.99 (0.98-0.99) per day increase]. Next to its association with BCV, M. haemolytica was more frequently detected in herds with 5 to 10 animals per pen [OR = 8.0 (1.4-46.9)] compared with <5 animals, and in herds with sawdust as bedding [OR = 18.3 (1.8-191.6)]. Also, for H. somni, housing on sawdust was a risk factor [OR = 5.2 (1.2-23.0)]. Purchase of cattle [OR = 2.9 (1.0-8.0)] and housing of recently purchased animals in the same airspace [OR = 5.0 (1.5-16.5)] were risk factors for M. bovis. This study identified pathogen-specific risk factors that might be useful for the development of customized control and prevention and for the design of decision support tools to justify antimicrobial use by predicting the most likely pathogen before sampling results are available.
Topics: Animals; Belgium; Bronchoalveolar Lavage; Cattle; Cattle Diseases; Coronavirus, Bovine; Cross-Sectional Studies; Disease Outbreaks; Feces; Female; Male; Mannheimia haemolytica; Mycoplasma bovis; Parainfluenza Virus 3, Bovine; Pasteurella multocida; Pasteurellaceae; Respiratory Syncytial Virus, Bovine; Respiratory Tract Infections; Risk Factors; Species Specificity; Surveys and Questionnaires
PubMed: 31954585
DOI: 10.3168/jds.2019-17486 -
Frontiers in Cellular and Infection... 2022is well-known for causing Glässer's disease, which costs the worldwide swine industry millions of dollars each year. It has been reported the symptom of pleural...
is well-known for causing Glässer's disease, which costs the worldwide swine industry millions of dollars each year. It has been reported the symptom of pleural thickening during Glässer's disease but this symptom has received little attention. And there is no research on the elements which promote pleural thickening. In this study, pleural thickening was discovered to be associated with increased collagen fibers and elastic fibers. Furthermore, collagen-I and elastin were found to be up-regulated and concentrated in the pleura at the mRNA and protein levels following infection. To summarize, our findings add to the theoretical understanding of Glässer's disease and provide strong support for further research into the pathogenic mechanism of and the program's target treatment.
Topics: Animals; Collagen; Elastin; Haemophilus Infections; Haemophilus parasuis; Swine; Swine Diseases
PubMed: 36034702
DOI: 10.3389/fcimb.2022.952377 -
Dental Press Journal of Orthodontics 2021Aggressive periodontitis causes periodontal destruction, with loss of supporting alveolar bone. The common symptom is rapid attachment loss in the first molar and...
INTRODUCTION
Aggressive periodontitis causes periodontal destruction, with loss of supporting alveolar bone. The common symptom is rapid attachment loss in the first molar and incisor area, in young adults.
OBJECTIVE
The aim of this study was to discuss the challenges, implications and the impact of orthodontic treatment in patients affected by severe periodontal problems, specifically aggressive periodontitis.
DISCUSSION
In addition to other bacteria, the main pathogen involved in aggressive periodontitis is the Aggregatibacter actinomycetemcomitans. However, the susceptibility to the disease differs among individuals, being immune deficiencies the main reason for this variability. Many orthodontists are not comfortable about performing treatments on individuals with aggressive periodontitis.
CONCLUSION
Orthodontic treatment is feasible in young patients with severe and localized aggressive periodontitis, as long as the limitations imposed by the disease are respected. An interdisciplinary approach is required, with frequent periodontal follow-up before, during and after orthodontic treatment, allowing the correction of dental positions without aggravating bone loss.
Topics: Aggregatibacter actinomycetemcomitans; Aggressive Periodontitis; Humans; Incisor; Molar; Young Adult
PubMed: 34932773
DOI: 10.1590/2177-6709.26.6.e21bbo6