scholarly journals Expression of the genes encoding the CasK/R two-component system and the DesA desaturase duringBacillus cereuscold adaptation

2016 ◽  
Vol 363 (16) ◽  
pp. fnw174 ◽  
Author(s):  
Sara Esther Diomandé ◽  
Bénédicte Doublet ◽  
Florian Vasaï ◽  
Marie-Hélène Guinebretière ◽  
Véronique Broussolle ◽  
...  
2007 ◽  
Vol 75 (5) ◽  
pp. 2421-2431 ◽  
Author(s):  
Lori A. Bibb ◽  
Carey A. Kunkle ◽  
Michael P. Schmitt

ABSTRACT Transcription of the Corynebacterium diphtheriae hmuO gene, which encodes a heme oxygenase involved in heme iron utilization, is activated in a heme- or hemoglobin-dependent manner in part by the two-component system ChrA-ChrS. Mutation of either the chrA or the chrS gene resulted in a marked reduction of hemoglobin-dependent activation at the hmuO promoter in C. diphtheriae; however, it was observed that significant levels of hemoglobin-dependent expression were maintained in the mutants, suggesting that an additional activator is involved in regulation. A BLAST search of the C. diphtheriae genome sequence revealed a second two-component system, encoded by DIP2268 and DIP2267, that shares similarity with ChrS and ChrA, respectively; we have designated these genes hrrS (DIP2268) and hrrA (DIP2267). Analysis of hmuO promoter expression demonstrated that hemoglobin-dependent activity was fully abolished in strains from which both the chrA-chrS and the hrrA-hrrS two-component systems were deleted. Similarly, deletion of the sensor kinase genes chrS and hrrS or the genes encoding both of the response regulators chrA and hrrA also eliminated hemoglobin-dependent activation at the hmuO promoter. We also show that the regulators ChrA-ChrS and HrrA-HrrS are involved in the hemoglobin-dependent repression of the promoter upstream of hemA, which encodes a heme biosynthesis enzyme. Evidence for cross talk between the ChrA-ChrS and HrrA-HrrS systems is presented. In conclusion, these findings demonstrate that the ChrA-ChrS and HrrA-HrrS regulatory systems are critical for full hemoglobin-dependent activation at the hmuO promoter and also suggest that these two-component systems are involved in the complex mechanism of the regulation of heme homeostasis in C. diphtheriae.


1998 ◽  
Vol 36 (9) ◽  
pp. 2471-2476 ◽  
Author(s):  
Juana Magdalena ◽  
Philip Supply ◽  
Camille Locht

A PCR procedure based on the intergenic region (IR) separating two genes encoding a recently identified mycobacterial two-component system, named SenX3-RegX3, was developed and was shown to be suitable for identifying Mycobacterium bovis BCG. ThesenX3-regX3 IR contains a novel type of repetitive sequence, called mycobacterial interspersed repetitive units (MIRUs). All tested BCG strains exclusively contained 77-bp MIRUs within the senX3-regX3 IR, whereas all non-BCGM. tuberculosis complex strains contained a 53-bp MIRU, in addition to the 77-bp MIRUs. All 148 strains analyzed so far could be divided into eight different groups according to the copy numbers of the 77-bp MIRU and to the presence or absence of the 53-bp MIRU. BCG strains contained either one, two, or three 77-bp MIRUs. The other strains contained one to five 77-bp MIRUs invariably followed by a 53-bp MIRU. The consistent absence of the 53-bp MIRU in BCG strains and its presence in virulent strains allowed us to develop an enzyme-linked immunosorbent assay using specific capture oligonucleotide probes to distinguish between BCG and other M. tuberculosis complex strains.


2009 ◽  
Vol 53 (9) ◽  
pp. 3628-3634 ◽  
Author(s):  
Mark D. Adams ◽  
Gabrielle C. Nickel ◽  
Saralee Bajaksouzian ◽  
Heather Lavender ◽  
A. Rekha Murthy ◽  
...  

ABSTRACT The mechanism of colistin resistance (Colr) in Acinetobacter baumannii was studied by selecting in vitro Colr derivatives of the multidrug-resistant A. baumannii isolate AB0057 and the drug-susceptible strain ATCC 17978, using escalating concentrations of colistin in liquid culture. DNA sequencing identified mutations in genes encoding the two-component system proteins PmrA and/or PmrB in each strain and in a Colr clinical isolate. A colistin-susceptible revertant of one Colr mutant strain, obtained following serial passage in the absence of colistin selection, carried a partial deletion of pmrB. Growth of AB0057 and ATCC 17978 at pH 5.5 increased the colistin MIC and conferred protection from killing by colistin in a 1-hour survival assay. Growth in ferric chloride [Fe(III)] conferred a small protective effect. Expression of pmrA was increased in Colr mutants, but not at a low pH, suggesting that additional regulatory factors remain to be discovered.


PLoS ONE ◽  
2013 ◽  
Vol 8 (2) ◽  
pp. e56063 ◽  
Author(s):  
Hamza Celik ◽  
Jean-Charles Blouzard ◽  
Birgit Voigt ◽  
Dörte Becher ◽  
Valentine Trotter ◽  
...  

mBio ◽  
2021 ◽  
Author(s):  
Matthew M. Schaefers ◽  
Benjamin X. Wang ◽  
Nicole M. Boisvert ◽  
Sarah J. Martini ◽  
Sarah L. Bonney ◽  
...  

Infections caused by members of the Burkholderia cepacia complex (BCC) are a serious concern for patients with cystic fibrosis (CF) as these bacteria are often resistant to many antibiotics. During long-term infection of CF patients with BCC, mutations in genes encoding the FixLJ system often become prevalent, suggesting that these changes may benefit the bacteria during infection.


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