Role of the Vibrio cholerae Matrix Protein Bap1 in Cross-Resistance to Antimicrobial Peptides

The emergence of antibiotic-resistant bacteria led to an urgent need for next-generation antimicrobial agents with novel mechanisms of action. The use of positively charged antimicrobial peptides that target cytoplasmic membrane is an especially promising strategy since essential functions and the conserved structure of the membrane hinder the development of bacterial resistance. Aureocin A53- and enterocin L50-like bacteriocins are highly cationic, membrane-targeting antimicrobial peptides that have potential as next-generation antibiotics. However, the mechanisms of resistance to these bacteriocins and cross-resistance against antibiotics must be examined before application to ensure their safe use. Here, in the model bacterium Lactococcus lactis, we studied the development of resistance to selected aureocin A53- and enterocin L50-like bacteriocins and its correlation with antibiotics. First, to generate spontaneous resistant mutants, L.lactis was exposed to bacteriocin BHT-B. Sequencing of their genomes revealed single nucleotide polymorphisms (SNPs) in the dgkB (yecE) and dxsA genes encoding diacylglycerol kinase and 1-deoxy-D-xylulose 5-phosphate synthase, respectively. Then, selected mutants underwent susceptibility tests with a wide array of bacteriocins and antibiotics. The highest alterations in the sensitivity of studied mutants were seen in the presence of cytoplasmic membrane targeting bacteriocins (K411, Ent7, EntL50, WelM, SalC, nisin) and antibiotics (daptomycin and gramicidin) as well as lipid II cycle-blocking bacteriocins (nisin and Lcn972) and antibiotics (bacitracin). Interestingly, decreased via the SNPs accumulation sensitivity to membrane-active bacteriocins and antibiotics resulted in the concurrently increased vulnerability to bacitracin, carbenicillin, or chlortetracycline. It is suspected that SNPs may result in alterations to the efficiency of the nascent enzymes rather than a total loss of their function as neither deletion nor overexpression of dxsA restored the phenotype observed in spontaneous mutants.

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The role of extracellular matrix protein 1 in human skin

Clinical and Experimental Dermatology ◽

10.1111/j.1365-2230.2004.01440.x ◽

2004 ◽

Vol 29 (1) ◽

pp. 52-56 ◽

Cited By ~ 58

Author(s):

I. Chan

Keyword(s):

Extracellular Matrix ◽

Human Skin ◽

Matrix Protein ◽

Extracellular Matrix Protein ◽

Extracellular Matrix Protein 1

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Mutation ofRv2887, amarR-Like Gene, Confers Mycobacterium tuberculosis Resistance to an Imidazopyridine-Based Agent

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01341-15 ◽

2015 ◽

Vol 59 (11) ◽

pp. 6873-6881 ◽

Cited By ~ 13

Author(s):

Kathryn Winglee ◽

Shichun Lun ◽

Marco Pieroni ◽

Alan Kozikowski ◽

William Bishai

Keyword(s):

Mycobacterium Tuberculosis ◽

Drug Targets ◽

Efflux Pump ◽

Transcriptional Regulator ◽

Cross Resistance ◽

Loss Of Function ◽

Strong Activity ◽

Content Type ◽

Novel Drug

ABSTRACTDrug resistance is a major problem inMycobacterium tuberculosiscontrol, and it is critical to identify novel drug targets and new antimycobacterial compounds. We have previously identified an imidazo[1,2-a]pyridine-4-carbonitrile-based agent, MP-III-71, with strong activity againstM. tuberculosis. In this study, we evaluated mechanisms of resistance to MP-III-71. We derived three independentM. tuberculosismutants resistant to MP-III-71 and conducted whole-genome sequencing of these mutants. Loss-of-function mutations inRv2887were common to all three MP-III-71-resistant mutants, and we confirmed the role ofRv2887as a gene required for MP-III-71 susceptibility using complementation. The Rv2887 protein was previously unannotated, but domain and homology analyses suggested it to be a transcriptional regulator in the MarR (multiple antibiotic resistance repressor) family, a group of proteins first identified inEscherichia colito negatively regulate efflux pumps and other mechanisms of multidrug resistance. We found that two efflux pump inhibitors, verapamil and chlorpromazine, potentiate the action of MP-III-71 and that mutation ofRv2887abrogates their activity. We also used transcriptome sequencing (RNA-seq) to identify genes which are differentially expressed in the presence and absence of a functional Rv2887 protein. We found that genes involved in benzoquinone and menaquinone biosynthesis were repressed by functional Rv2887. Thus, inactivating mutations ofRv2887, encoding a putative MarR-like transcriptional regulator, confer resistance to MP-III-71, an effective antimycobacterial compound that shows no cross-resistance to existing antituberculosis drugs. The mechanism of resistance ofM. tuberculosisRv2887mutants may involve efflux pump upregulation and also drug methylation.

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Pathogenic role of Fgf23 in Dmp1-null mice

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.90201.2008 ◽

2008 ◽

Vol 295 (2) ◽

pp. E254-E261 ◽

Cited By ~ 96

Author(s):

Shiguang Liu ◽

Jianping Zhou ◽

Wen Tang ◽

Rochelle Menard ◽

Jian Q. Feng ◽

...

Keyword(s):

Growth Retardation ◽

Matrix Protein ◽

Serum Levels ◽

Serum Phosphate ◽

Hypophosphatemic Rickets ◽

Null Mouse ◽

Matrix Mineralization ◽

Severe Growth ◽

Inactivating Mutations

Autosomal recessive hypophosphatemic rickets (ARHR), which is characterized by renal phosphate wasting, aberrant regulation of 1α-hydroxylase activity, and rickets/osteomalacia, is caused by inactivating mutations of dentin matrix protein 1 ( DMP1). ARHR resembles autosomal dominant hypophosphatemic rickets (ADHR) and X-linked hypophosphatemia (XLH), hereditary disorders respectively caused by cleavage-resistant mutations of the phosphaturic factor FGF23 and inactivating mutations of PHEX that lead to increased production of FGF23 by osteocytes in bone. Circulating levels of FGF23 are increased in ARHR and its Dmp1-null mouse homologue. To determine the causal role of FGF23 in ARHR, we transferred Fgf23 deficient/enhanced green fluorescent protein (eGFP) reporter mice onto Dmp1-null mice to create mice lacking both Fgf23 and Dmp1. Dmp1−/− mice displayed decreased serum phosphate concentrations, inappropriately normal 1,25(OH)2D levels, severe rickets, and a diffuse form of osteomalacia in association with elevated Fgf23 serum levels and expression in osteocytes. In contrast, Fgf23−/− mice had undetectable serum Fgf23 and elevated serum phosphate and 1,25(OH)2D levels along with severe growth retardation and focal form of osteomalacia. In combined Dmp1−/−/Fgf23−/−, circulating Fgf23 levels were also undetectable, and the serum levels of phosphate and 1,25(OH)2D levels were identical to Fgf23−/− mice. Rickets and diffuse osteomalacia in Dmp1-null mice were transformed to severe growth retardation and focal osteomalacia characteristic of Fgf23-null mice. These data suggest that the regulation of extracellular matrix mineralization by DMP1 is coupled to renal phosphate handling and vitamin D metabolism through a DMP1-dependent regulation of FGF23 production by osteocytes.

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Indole Acts as an Extracellular Cue Regulating Gene Expression in Vibrio cholerae

Journal of Bacteriology ◽

10.1128/jb.01240-08 ◽

2009 ◽

Vol 191 (11) ◽

pp. 3504-3516 ◽

Cited By ~ 109

Author(s):

Ryan S. Mueller ◽

Sinem Beyhan ◽

Simran G. Saini ◽

Fitnat H. Yildiz ◽

Douglas H. Bartlett

Keyword(s):

Gene Expression ◽

Vibrio Cholerae ◽

Biofilm Formation ◽

Signal Molecule ◽

Control Of Gene Expression ◽

Protozoan Grazing ◽

Extracellular Signal ◽

Grazing Resistance ◽

Indole Signaling

ABSTRACT Indole has been proposed to act as an extracellular signal molecule influencing biofilm formation in a range of bacteria. For this study, the role of indole in Vibrio cholerae biofilm formation was examined. It was shown that indole activates genes involved in vibrio polysaccharide (VPS) production, which is essential for V. cholerae biofilm formation. In addition to activating these genes, it was determined using microarrays that indole influences the expression of many other genes, including those involved in motility, protozoan grazing resistance, iron utilization, and ion transport. A transposon mutagenesis screen revealed additional components of the indole-VPS regulatory circuitry. The indole signaling cascade includes the DksA protein along with known regulators of VPS production, VpsR and CdgA. A working model is presented in which global control of gene expression by indole is coordinated through σ54 and associated transcriptional regulators.

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