Induction of the Nitrate Assimilation
            <i>nirA</i>
            Operon and Protein-Protein Interactions in the Maturation of Nitrate and Nitrite Reductases in the Cyanobacterium Anabaena sp. Strain PCC 7120

Frías, José E.; Flores, Enrique

doi:10.1128/jb.00198-15

Cited by 16 publications

(9 citation statements)

References 47 publications

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“…Na 2 CO 3 was used to stop the reaction, and the turbidity was measured at 420 nm. The β‐galactosidase activity (Miller units) was calculated as described previously (Frias and Flores, ). For the production of the HigA, HigBA complex and MHigB‐HigA, strains containing pMQ70, pMQ70‐ higA, pMQ70‐ higBA and pMQ70‐M higBA were induced with 10 mM L ‐arabinose.…”

Section: Methodsmentioning

confidence: 99%

Antitoxin HigA inhibits virulence gene mvfR expression in Pseudomonas aeruginosa

Guo

Sun

et al. 2019

Environmental Microbiology

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Summary Toxin/antitoxin (TA) systems are ubiquitous in bacteria and archaea and participate in biofilm formation and stress responses. The higBA locus of the opportunistic pathogen Pseudomonas aeruginosa encodes a type II TA system. Previous work found that the higBA operon is cotranscribed and that HigB toxin regulates biofilm formation and virulence expression. In this study, we demonstrate that HigA antitoxin is produced at a higher level than HigB and that higA mRNA is expressed separately from a promoter inside higB during the late stationary phase. Critically, HigA represses the expression of mvfR, which is an important virulence‐related regulator, by binding to a conserved HigA palindrome (5′‐TTAAC GTTAA‐3′) in the mvfR promoter, and the binding of HigB to HigA derepresses this process. During the late stationary phase, excess HigA represses the expression of mvfR and higBA. However, in the presence of aminoglycoside antibiotics where Lon protease is activated, the degradation of HigA by Lon increases P. aeruginosa virulence by simultaneously derepressing mvfR and higB transcription. Therefore, this study reveals that the antitoxin of the P. aeruginosa TA system is integrated into the key virulence regulatory network of the host and functions as a transcriptional repressor to control the production of virulence factors.

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Section: Methodsmentioning

confidence: 99%

Antitoxin HigA inhibits virulence gene mvfR expression in Pseudomonas aeruginosa

Guo

Sun

et al. 2019

Environmental Microbiology

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“…Next, 500 l of 1 M Na 2 CO 3 was added to stop the reactions and the turbidity at 420 nm was measured. The ␤-galactosidase activity (Miller units) was calculated as described previously (70). For rpoS complementation studies, cells carrying pCA24N-rpoS were cultured to a turbidity at 600 nm of 1.0, and the expression of RpoS was induced with 0.5 mM IPTG for 2 h; ␤-galactosidase activity was measured as above.…”

Section: Methodsmentioning

confidence: 99%

Tail-Anchored Inner Membrane Protein ElaB Increases Resistance to Stress While Reducing Persistence in Escherichia coli

Guo

Liu

et al. 2017

J Bacteriol

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Host-associated bacteria, such as , often encounter various host-related stresses, such as nutritional deprivation, oxidative stress, and temperature shifts. There is growing interest in searching for small endogenous proteins that mediate stress responses. Here, we characterized the small C-tail-anchored inner membrane protein ElaB in ElaB belongs to a class of tail-anchored inner membrane proteins with a C-terminal transmembrane domain but lacking an N-terminal signal sequence for membrane targeting. Proteins from this family have been shown to play vital roles, such as in membrane trafficking and apoptosis, in eukaryotes; however, their role in prokaryotes is largely unexplored. Here, we found that the transcription of is induced in the stationary phase in and stationary-phase sigma factor RpoS regulates transcription by binding to the promoter of Moreover, ElaB protects cells against oxidative stress and heat shock stress. However, unlike membrane peptide toxins TisB and GhoT, ElaB does not lead to cell death, and the deletion of greatly increases persister cell formation. Therefore, we demonstrate that disruption of C-tail-anchored inner membrane proteins can reduce stress resistance; it can also lead to deleterious effects, such as increased persistence, in synthesizes dozens of poorly understood small membrane proteins containing a predicted transmembrane domain. In this study, we characterized the function of the C-tail-anchored inner membrane protein ElaB in ElaB increases resistance to oxidative stress and heat stress, while inactivation of ElaB leads to high persister cell formation. We also demonstrated that the transcription of is under the direct regulation of stationary-phase sigma factor RpoS. Thus, our study reveals that small inner membrane proteins may have important cellular roles during the stress response.

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“…The ntcB gene is expressed also from a Class II NtcA‐activated promoter (Frías et al ., ). Further, the products of two genes, nirB and narM , are needed to attain high levels of activity of nitrite reductase and nitrate reductase respectively, and NirA‐NirB and NarB‐NarM protein–protein interactions have been found to take place (Frías and Flores, ; ). High levels of expression of the operon are observed only if nitrate or nitrite (which can be considered physiological inducers) is available.…”

Section: Assimilation Of Combined N Sources Alternative To Ammoniummentioning

confidence: 99%

Genetic responses to carbon and nitrogen availability in Anabaena

Herrero

Flores

2018

Environmental Microbiology

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Heterocyst-forming cyanobacteria are filamentous organisms that perform oxygenic photosynthesis and CO fixation in vegetative cells and nitrogen fixation in heterocysts, which are formed under deprivation of combined nitrogen. These organisms can acclimate to use different sources of nitrogen and respond to different levels of CO . Following work mainly done with the best studied heterocyst-forming cyanobacterium, Anabaena, here we summarize the mechanisms of assimilation of ammonium, nitrate, urea and N , the latter involving heterocyst differentiation, and describe aspects of CO assimilation that involves a carbon concentration mechanism. These processes are subjected to regulation establishing a hierarchy in the assimilation of nitrogen sources -with preference for the most reduced nitrogen forms- and a dependence on sufficient carbon. This regulation largely takes place at the level of gene expression and is exerted by a variety of transcription factors, including global and pathway-specific transcriptional regulators. NtcA is a CRP-family protein that adjusts global gene expression in response to the C-to-N balance in the cells, and PacR is a LysR-family transcriptional regulator (LTTR) that extensively acclimates the cells to oxygenic phototrophy. A cyanobacterial-specific transcription factor, HetR, is involved in heterocyst differentiation, and other LTTR factors are specifically involved in nitrate and CO assimilation.

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Induction of the Nitrate Assimilation nirA Operon and Protein-Protein Interactions in the Maturation of Nitrate and Nitrite Reductases in the Cyanobacterium Anabaena sp. Strain PCC 7120

Cited by 16 publications

References 47 publications

Antitoxin HigA inhibits virulence gene mvfR expression in Pseudomonas aeruginosa

Antitoxin HigA inhibits virulence gene mvfR expression in Pseudomonas aeruginosa

Tail-Anchored Inner Membrane Protein ElaB Increases Resistance to Stress While Reducing Persistence in Escherichia coli

Genetic responses to carbon and nitrogen availability in Anabaena

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