Dicarboximide resistance in field isolates of Alternaria alternata is mediated by a mutation in a two-component histidine kinase gene

2004 ◽  
Vol 41 (1) ◽  
pp. 102-108 ◽  
Author(s):  
Ian B Dry ◽  
Khor H Yuan ◽  
Don G Hutton
2006 ◽  
Vol 62 (10) ◽  
pp. 991-998 ◽  
Author(s):  
Zhonghua Ma ◽  
Yong Luo ◽  
Themis Michailides

Microbiology ◽  
2004 ◽  
Vol 150 (2) ◽  
pp. 447-453 ◽  
Author(s):  
Degang Ning ◽  
Xudong Xu

Anabaena sp. PCC 7120 was mutagenized by transposon Tn5-1087b, generating a mutant whose heterocysts lack the envelope polysaccharide layer. The transposon was located between nucleotides 342 and 343 of alr0117, a 918 bp gene encoding a histidine kinase for a two-component regulatory system. Complementation of the mutant with a DNA fragment containing alr0117 and targeted inactivation of the gene confirmed that alr0117 is involved in heterocyst development. RT-PCR showed that alr0117 was constitutively expressed in the presence or absence of a combined-nitrogen source. hepA and patB, the two genes turned on during wild-type heterocyst development, were no longer activated in an alr0117-null mutant. The two-component signal transduction system involving alr0117 may control the formation of the envelope polysaccharide layer and certain late events essential to the function of heterocysts.


2001 ◽  
Vol 57 (5) ◽  
pp. 437-442 ◽  
Author(s):  
Noriyuki Ochiai ◽  
Makoto Fujimura ◽  
Takayuki Motoyama ◽  
Akihiko Ichiishi ◽  
Ron Usami ◽  
...  

2006 ◽  
Vol 72 (1) ◽  
pp. 65-73 ◽  
Author(s):  
Michiyo Oshima ◽  
Shinpei Banno ◽  
Kiyotsugu Okada ◽  
Taeko Takeuchi ◽  
Makoto Kimura ◽  
...  

2017 ◽  
Vol 199 (22) ◽  
Author(s):  
Qing Chen ◽  
Victoria Ng ◽  
Jason M. Warfel ◽  
Tod J. Merkel ◽  
Scott Stibitz

ABSTRACT The two-component response regulator RisA, encoded by open reading frame BP3554 in the Bordetella pertussis Tohama I genomic sequence, is a known activator of vrg genes, a set of genes whose expression is increased under the same environmental conditions (known as modulation) that result in repression of the bvgAS virulence regulon. Here we demonstrate that RisA is phosphorylated in vivo and that RisA phosphorylation is required for activation of vrg genes. An adjacent histidine kinase gene, risS, is truncated by frameshift mutation in B. pertussis but not in Bordetella bronchiseptica or Bordetella parapertussis. Neither deletion of risS′ or bvgAS nor phenotypic modulation with MgSO4 affected levels of phosphorylated RisA (RisA∼P) in B. pertussis. However, RisA phosphorylation did require the histidine kinase encoded by BP3223, here named RisK (cognate histidine kinase of RisA). RisK was also required for expression of the vrg genes. This requirement could be obviated by the introduction of the phosphorylation-mimicking RisAD60E mutant, indicating that an active conformation of RisA, but not phosphorylation per se, is crucial for vrg activation. Interestingly, expression of vrg genes is still modulated by MgSO4 in cells harboring the RisAD60E mutation, suggesting that the activated RisA senses additional signals to control vrg expression in response to environmental stimuli. IMPORTANCE In B. pertussis, the BvgAS two-component system activates the expression of virulence genes by binding of BvgA∼P to their promoters. Expression of the reciprocally regulated vrg genes requires RisA and is also repressed by the Bvg-activated BvgR. RisA is an OmpR-like response regulator, but RisA phosphorylation was not expected because the gene for its presumed, cooperonic, histidine kinase is inactivated by mutation. In this study, we demonstrate phosphorylation of RisA in vivo by a noncooperonic histidine kinase. We also show that RisA phosphorylation is necessary but not sufficient for vrg activation but, importantly, is not affected by BvgAS status. Instead, we propose that vrg expression is controlled by BvgAS through its regulation of BvgR, a cyclic di-GMP (c-di-GMP) phosphodiesterase.


2002 ◽  
Vol 70 (2) ◽  
pp. 985-987 ◽  
Author(s):  
Antonella Torosantucci ◽  
Paola Chiani ◽  
Flavia De Bernardis ◽  
Antonio Cassone ◽  
Jose Antonio Calera ◽  
...  

ABSTRACT We have observed that human neutrophils (polymorphonuclear leukocytes [PMNs]) have an increased growth-inhibitory and killing effect on a strain of Candida albicans with a deletion of CHK1, a gene encoding a putative histidine kinase. The PMN effect was not due to increased phagocytosis of the null strain. This observation may partially explain the reduced virulence in a hematogenously disseminated murine model of candidiasis.


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