scholarly journals Mutations of folC cause increased susceptibility to sulfamethoxazole in Mycobacterium tuberculosis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ruiqi Wang ◽  
Kun Li ◽  
Jifang Yu ◽  
Jiaoyu Deng ◽  
Yaokai Chen
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Type Strain ◽  
Wild Type Strain ◽  
Clinical Isolates ◽  
Aminobenzoic Acid ◽  
Wild Type ◽  
Dihydropteroate Synthase ◽  
Expression Levels ◽  
Encoding Gene ◽  
Increased Susceptibility

AbstractPrevious studies showed that mutation of folC caused decreased expression of the dihydropteroate synthase encoding gene folP2 in Mycobacterium tuberculosis (M. tuberculosis). We speculated that mutation of folC in M. tuberculosis might affect the susceptibility to sulfamethoxazole (SMX). To prove this, 53 clinical isolates with folC mutations were selected and two folC mutants (I43A, I43T) were constructed based on M. tuberculosis H37Ra. The results showed that 42 of the 53 clinical isolates (79.2%) and the two lab-constructed folC mutants were more sensitive to SMX. To probe the mechanism by which folC mutations make M. tuberculosis more sensitive to SMX, folP2 was deleted in H37Ra, and expression levels of folP2 were compared between H37Ra and the two folC mutants. Although deletion of folP2 resulted in increased susceptibility to SMX, no difference in folP2 expression was observed. Furthermore, production levels of para-aminobenzoic acid (pABA) were compared between the folC mutants and the wild-type strain, and results showed that folC mutation resulted in decreased production of pABA. Taken together, we show that folC mutation leads to decreased production of pABA in M. tuberculosis and thus affects its susceptibility to SMX, which broadens our understanding of mechanisms of susceptibilities to antifolates in this bacterium.

scholarly journals Activation of 2,4-Diaminoquinazoline in Mycobacterium tuberculosis by Rv3161c, a Putative Dioxygenase

2018 ◽  
Vol 63 (1) ◽  
Author(s):  
Eduard Melief ◽  
Shilah A. Bonnett ◽  
Edison S. Zuniga ◽  
Tanya Parish
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Mutant Strain ◽  
Type Strain ◽  
Wild Type Strain ◽  
Type A ◽  
Wild Type ◽  
Metabolite Analysis ◽  
Content Type ◽  
Data Support ◽  
In The Wild

ABSTRACT The diaminoquinazoline series has good potency against Mycobacterium tuberculosis. Resistant isolates have mutations in Rv3161c, a putative dioxygenase. We carried out metabolite analysis on a wild-type strain and an Rv3161c mutant strain after exposure to a diaminoquinazoline. The parental compound was found in intracellular extracts from the mutant but not the wild type. A metabolite consistent with a monohydroxylated form was identified in the wild type. These data support the hypothesis that Rv3161c metabolizes diaminoquinazolines in M. tuberculosis.

scholarly journals Inactivation of traP Has No Effect on the Agr Quorum-Sensing System or Virulence of Staphylococcus aureus

2007 ◽  
Vol 75 (9) ◽  
pp. 4519-4527 ◽  
Author(s):  
Lindsey N. Shaw ◽  
Ing-Marie Jonsson ◽  
Vineet K. Singh ◽  
Andrej Tarkowski ◽  
George C. Stewart
Keyword(s):  
Staphylococcus Aureus ◽  
Quorum Sensing ◽  
Type Strain ◽  
Wild Type Strain ◽  
Surface Proteins ◽  
Virulence Determinants ◽  
Wild Type ◽  
Expression Levels ◽  
Sensing System ◽  
Quorum Sensing System

ABSTRACT The success of Staphylococcus aureus as a pathogen can largely be attributed to the plethora of genetic regulators encoded within its genome that temporally regulate its arsenal of virulence determinants throughout its virulence lifestyle. Arguably the most important of these is the two-component, quorum-sensing system agr. Over the last decade, the controversial presence of a second quorum-sensing system (the TRAP system) has been proposed, and it has been mooted to function as the master regulator of virulence in S. aureus by modulating agr. Mutants defective in TRAP are reported to be devoid of agr expression, lacking in hemolytic activity, essentially deficient in the secretion of virulence determinants, and avirulent in infection models. A number of research groups have questioned the validity of the TRAP findings in recent years; however, a thorough and independent analysis of its role in S. aureus physiology and pathogenesis has not been forthcoming. Therefore, we have undertaken such an analysis of the TRAP locus of S. aureus. We found that a traP mutant was equally hemolytic as the wild-type strain. Furthermore, transcriptional profiling found no alterations in the traP mutant in expression levels of agr or in expression levels of multiple agr-regulated genes (hla, sspA, and spa). Analysis of secreted and surface proteins of the traP mutant revealed no deviation in comparison to the parent. Finally, analysis conducted using a murine model of S. aureus septic arthritis revealed that, in contrast to an agr mutant, the traP mutant was just as virulent as the wild-type strain.

scholarly journals d-Alanylation of Lipoteichoic Acid Contributes to the Virulence of Streptococcus suis

2008 ◽  
Vol 76 (8) ◽  
pp. 3587-3594 ◽  
Author(s):  
Nahuel Fittipaldi ◽  
Tsutomu Sekizaki ◽  
Daisuke Takamatsu ◽  
Josée Harel ◽  
María de la Cruz Domínguez-Punaro ◽  
...  
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Streptococcus Suis ◽  
Lipoteichoic Acid ◽  
Microvascular Endothelial Cells ◽  
Wild Type ◽  
Immune Clearance ◽  
Allelic Replacement ◽  
Swine Pathogen ◽  
Increased Susceptibility

ABSTRACT We generated by allelic replacement a ΔdltA mutant of a virulent Streptococcus suis serotype 2 field strain and evaluated the contribution of lipoteichoic acid (LTA) d-alanylation to the virulence traits of this swine pathogen and zoonotic agent. The absence of LTA d-alanylation resulted in increased susceptibility to the action of cationic antimicrobial peptides. In addition, and in contrast to the wild-type strain, the ΔdltA mutant was efficiently killed by porcine neutrophils and showed diminished adherence to and invasion of porcine brain microvascular endothelial cells. Finally, the ΔdltA mutant was attenuated in both the CD1 mouse and porcine models of infection, probably reflecting a decreased ability to escape immune clearance mechanisms and an impaired capacity to move across host barriers. The results of this study suggest that LTA d-alanylation is an important factor in S. suis virulence.

scholarly journals Fitness Cost of Rifampin Resistance in Neisseria meningitidis:In VitroStudy of Mechanisms Associated withrpoBH553Y Mutation

2015 ◽  
Vol 59 (12) ◽  
pp. 7637-7649 ◽  
Author(s):  
Roberta Colicchio ◽  
Chiara Pagliuca ◽  
Gabiria Pastore ◽  
Annunziata Gaetana Cicatiello ◽  
Caterina Pagliarulo ◽  
...  
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Capsular Polysaccharide ◽  
Culture Media ◽  
Point Mutations ◽  
Clinical Isolates ◽  
Sequencing Analysis ◽  
Wild Type ◽  
Rifampin Resistance

ABSTRACTRifampin chemoprophylaxis againstNeisseria meningitidisinfections led to the onset of rifampin resistance in clinical isolates harboring point mutations in therpoBgene, coding for the RNA polymerase β chain. These resistant strains are rare in medical practice, suggesting their decreased fitness in the human host. In this study, we isolated rifampin-resistantrpoBmutants from hypervirulent serogroup C strain 93/4286 and analyzed their different properties, including the ability to grow/survive in different culture media and in differentiated THP-1 human monocytes and to compete with the wild-type strainin vitro. Our results demonstrate that differentrpoBmutations (H553Y, H553R, and S549F) may have different effects, ranging from low- to high-cost effects, on bacterial fitnessin vitro. Moreover, we found that the S549F mutation confers temperature sensitivity, possibly explaining why it is observed very rarely in clinical isolates. Comparative high-throughput RNA sequencing analysis of bacteria grown in chemically defined medium demonstrated that the low-cost H553Y substitution resulted in global transcriptional changes that functionally mimic the stringent response. Interestingly, many virulence-associated genes, including those coding for meningococcal type IV pili, porin A, adhesins/invasins, IgA protease, two-partner secretion system HrpA/HrpB, enzymes involved in resistance to oxidative injury, lipooligosaccharide sialylation, and capsular polysaccharide biosynthesis, were downregulated in the H553Y mutant compared to their level of expression in the wild-type strain. These data might account for the reduced capacity of this mutant to grow/survive in differentiated THP-1 cells and explain the rarity of H553Y mutants among clinical isolates.

scholarly journals Role of Mycobacterium tuberculosis Ser/Thr Kinase PknF: Implications in Glucose Transport and Cell Division

2005 ◽  
Vol 187 (10) ◽  
pp. 3415-3420 ◽  
Author(s):  
Parampal Deol ◽  
Reena Vohra ◽  
Adesh Kumar Saini ◽  
Amit Singh ◽  
Harish Chandra ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Glucose Transport ◽  
Stress Responses ◽  
Type Strain ◽  
Wild Type Strain ◽  
Physiological Role ◽  
Wild Type ◽  
Bacterial Physiology ◽  
Transport Analysis

ABSTRACT Protein kinases have a diverse array of functions in bacterial physiology, with a distinct role in the regulation of development, stress responses, and pathogenicity. pknF, one of the 11 kinases of Mycobacterium tuberculosis, encodes an autophosphorylating, transmembrane serine/threonine protein kinase, which is absent in the fast-growing, nonpathogenic Mycobacterium smegmatis. Herein, we investigate the physiological role of PknF using an antisense strategy with M. tuberculosis and expressing PknF and its kinase mutant (K41M) in M. smegmatis. Expression of PknF in M. smegmatis led to reduction in the growth rate and shortening and swelling of cells with constrictions. Interestingly, an antisense strain of M. tuberculosis expressing a low level of PknF displayed fast growth and a deformed cell morphology compared to the wild-type strain. Electron microscopy showed that most of the cells of the antisense strain were of a smaller size with an aberrant septum. Furthermore, nutrient transport analysis of these strains was conducted using 3H-labeled and 14C-labeled substrates. A significant increase in the uptake of d-glucose but not of glycerol, leucine, or oleic acid was observed in the antisense strain compared to the wild-type strain. The results suggest that PknF plays a direct/indirect role in the regulation of glucose transport, cell growth, and septum formation in M. tuberculosis.

scholarly journals Involvement of Efflux Pumps in the Resistance to Peptidoglycan Synthesis Inhibitors in Mycobacterium tuberculosis

2013 ◽  
Vol 57 (4) ◽  
pp. 1941-1943 ◽  
Author(s):  
Neela Dinesh ◽  
Sreevalli Sharma ◽  
Meenakshi Balganesh
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Type Strain ◽  
Wild Type Strain ◽  
Efflux Pump ◽  
Efflux Pumps ◽  
Wild Type ◽  
Intrinsic Resistance ◽  
Content Type ◽  
Peptidoglycan Synthesis

ABSTRACTWe evaluated the contributions ofMycobacterium tuberculosisefflux pumps towards intrinsic resistance to different classes of peptidoglycan synthesis inhibitors (PSI). Our study indicates that the efflux pump knockout strains are more susceptible to PSI than the wild type. Vancomycin and ceftriaxone exhibited up to 3 log increased kill on efflux pump mutants compared to the wild-type strain, strongly suggesting an important role for efflux pumps in the intrinsic resistance ofM. tuberculosisto PSI.

scholarly journals Role of Stress Response Sigma Factor SigG in Mycobacterium tuberculosis

2007 ◽  
Vol 190 (3) ◽  
pp. 1128-1133 ◽  
Author(s):  
Jong-Hee Lee ◽  
Deborah E. Geiman ◽  
William R. Bishai
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Type Strain ◽  
Wild Type Strain ◽  
Sos Response ◽  
Wild Type ◽  
Recognition Sequence ◽  
Reverse Transcription Pcr ◽  
Promoter Recognition ◽  
Microarray Studies

ABSTRACT The sigG gene of Mycobacterium tuberculosis was disrupted by homologous recombination, and the genes regulated by SigG were examined by real-time reverse-transcription PCR and microarray studies. The SigG consensus promoter recognition sequence was identified as GCGNGT-N15-18-CGANCA. A ΔsigG mutant was found to be more resistant to mitomycin C treatment than the wild-type strain, indicating that it may be involved in the SOS response in M. tuberculosis.

scholarly journals Overexpression of MexCD-OprJ Reduces Pseudomonas aeruginosa Virulence by Increasing Its Susceptibility to Complement-Mediated Killing

2014 ◽  
Vol 58 (4) ◽  
pp. 2426-2429 ◽  
Author(s):  
Inmaculada Martínez-Ramos ◽  
Xavier Mulet ◽  
Bartolomé Moyá ◽  
Mariette Barbier ◽  
Antonio Oliver ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antibiotic Resistance ◽  
Immune System ◽  
Antimicrobial Resistance ◽  
Type Strain ◽  
Wild Type Strain ◽  
Host Immune System ◽  
Wild Type ◽  
Content Type ◽  
Increased Susceptibility

ABSTRACTWe evaluated the resistance to complement-mediated killing of a collection of isogenicPseudomonas aeruginosastrains expressing different antimicrobial resistance phenotypes. Only thenfxBmutant demonstrated increased susceptibility to complement compared with that for the wild-type strain. This increment was due to the overexpression of MexCD-OprJ, which led to increased C3 opsonization and a reduced ability to infect the lungs of mice. Our results show that the acquisition of antibiotic resistance may alter the interplay ofP. aeruginosawith the host immune system.

scholarly journals Decreased C3 Activation by the devR Gene-Disrupted Mycobacterium tuberculosis Strain in Comparison to the Wild-Type Strain

2013 ◽  
Vol 2013 ◽  
pp. 1-5
Author(s):  
V. Narayan Rao ◽  
S. Manivannan ◽  
J. S. Tyagi ◽  
V. D. Ramanathan
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Complement Activation ◽  
Type Strain ◽  
Wild Type Strain ◽  
Solid Phase ◽  
Wild Strain ◽  
Tuberculosis Infection ◽  
Wild Type ◽  
Complement Component C3

Activation of the complement component C3 is an important step in the complement cascade, contributing to inflammatory mechanisms. Considerable research on gene-disrupted mycobacterial strains using animal models of tuberculosis infection has reported the roles of some of the mycobacterial genes during tuberculosis infection. The aim of the present study was to assess the pattern of complement activation by the devR gene-disrupted Mycobacterium tuberculosis H37Rv strain and compare with that by its wild-type strain. In vitro complement activation at the level of C3 by the gene-disrupted strain, its complemented strain, and wild-type strain was performed using solid-phase ELISA. It was observed that the ability of devR gene-disrupted M. tuberculosis H37Rv to activate C3 was significantly reduced in comparison to its wild-type strain (P<0.05). In addition, C3 activation by the complemented devR mutant strain was almost similar to that of the wild strain, which indicated that the reduced ability to activate C3 could potentially be due to the deletion of devR gene. These findings indicate that the gene devR probably aids in complement activation and contributes to the inflammatory processes during tuberculosis infection.

scholarly journals The Extra Cytoplasmic Function Sigma Factor σE Is Essential for Mycobacterium tuberculosis Virulence in Mice

2004 ◽  
Vol 72 (5) ◽  
pp. 3038-3041 ◽  
Author(s):  
Riccardo Manganelli ◽  
Lanfranco Fattorini ◽  
Dejiang Tan ◽  
Elisabetta Iona ◽  
Graziella Orefici ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Animal Models ◽  
Sigma Factor ◽  
Type Strain ◽  
Wild Type Strain ◽  
Wild Type ◽  
Immunocompetent Mice ◽  
Different Characteristics

ABSTRACT The virulence of a Mycobacterium tuberculosis H37Rv sigE mutant was studied in immunodeficient and immunocompetent mice. The mutant was strongly attenuated in both animal models and induced formation of granulomas with different characteristics than those induced by the wild-type strain.

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