NmtA, a novel metallothionein of Anabaena sp. strain PCC 7120 imparts protection against cadmium stress but not oxidative stress

Divya, T. V.; Chandwadkar, Pallavi; Acharya, Celin

doi:10.1016/j.aquatox.2018.03.035

Cited by 21 publications

(11 citation statements)

References 51 publications

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“…5C ). Consistent with our results, NG-20 has been reported to play a key role in Cd tolerance in Nostoc 7120 ( 67 ). Additionally, a number of Cd/Hg metabolism-related proteins were also identified using protein sequence alignment and functional annotation (Table S9).…”

Section: Discussionsupporting

confidence: 93%

Proteogenomic Analysis Provides Novel Insight into Genome Annotation and Nitrogen Metabolism in Nostoc sp. PCC 7120

Yang

Xiong

et al. 2021

Microbiol Spectr

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Cyanobacteria are a large group of prokaryotes capable of oxygenic photosynthesis and play a vital role in nitrogen and carbon cycles on Earth. Nostoc 7120 is a commonly used model cyanobacterium for studying cell differentiation and nitrogen metabolism. In this study, we presented the first comprehensive draft map of the Nostoc 7120 proteome and a wide range of posttranslational modifications.

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Section: Discussionsupporting

confidence: 93%

Proteogenomic Analysis Provides Novel Insight into Genome Annotation and Nitrogen Metabolism in Nostoc sp. PCC 7120

Yang

Xiong

et al. 2021

Microbiol Spectr

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“…Notably, MT1 is widely expressed in almost every organ to maintain homeostasis. Therefore, it has been most extensively investigated in recent decades (4,7,10,(13)(14)(15)(16)(17)(18)(19)(20)(21).…”

Section: Introductionmentioning

confidence: 99%

Metallothionein 1: A New Spotlight on Inflammatory Diseases

Dai

Wang

et al. 2021

Front. Immunol.

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MT1 has been demonstrated to be an essential stress protein in maintaining physiological balance and regulating immune homeostasis. While the immunological involvement of MT1 in central nervous system disorders and cancer has been extensively investigated, mounting evidence suggests that MT1 has a broader role in inflammatory diseases and can shape innate and adaptive immunity. In this review, we will first summarize the biological features of MT1 and the regulators that influence MT1 expression, emphasizing metal, inflammation, and immunosuppressive factors. We will then focus on the immunoregulatory function of MT1 on diverse immune cells and the signaling pathways regulated by MT1. Finally, we will discuss recent advances in our knowledge of the biological role of MT1 in several inflammatory diseases to develop novel therapeutic strategies.

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“…Overexpression of NmtA in its native strain conferred tolerance to cadmium stress (Divya et al, 2018). We had observed increased abundance of the nmtA transcripts in the presence of elevated concentrations of metal ions like Zn 2+ , Cu 2+ , and Cd 2+ (Divya et al, 2018), indicating transcriptional regulation of nmtA expression. It is proposed that the expression of the proteins associated with metal homeostasis is largely regulated at the transcriptional level in bacteria (Finney and O'Halloran, 2003).…”

Section: Introductionmentioning

confidence: 93%

“…Previously, we had identified and characterized a MT from the heterocystous, filamentous cyanobacterium Anabaena 7120 (also belonging to the BmtA family) referred to as NmtA. Overexpression of NmtA in its native strain conferred tolerance to cadmium stress (Divya et al, 2018). We had observed increased abundance of the nmtA transcripts in the presence of elevated concentrations of metal ions like Zn 2+ , Cu 2+ , and Cd 2+ (Divya et al, 2018), indicating transcriptional regulation of nmtA expression.…”

Section: Introductionmentioning

confidence: 97%

AzuR From the SmtB/ArsR Family of Transcriptional Repressors Regulates Metallothionein in Anabaena sp. Strain PCC 7120

Divya

Acharya

2022

Front. Microbiol.

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Metallothioneins (MTs) are cysteine-rich, metal-sequestering cytosolic proteins that play a key role in maintaining metal homeostasis and detoxification. We had previously characterized NmtA, a MT from the heterocystous, nitrogen-fixing cyanobacterium Anabaena sp. strain PCC 7120 and demonstrated its role in providing protection against cadmium toxicity. In this study, we illustrate the regulation of Anabaena NmtA by AzuR (Alr0831) belonging to the SmtB/ArsR family of transcriptional repressors. There is currently no experimental evidence for any functional role of AzuR. It is observed that azuR is located within the znuABC operon but in the opposite orientation and remotely away from the nmtA locus. Sequence analysis of AzuR revealed a high degree of sequence identity with Synechococcus SmtB and a distinct α5 metal binding site similar to that of SmtB. In order to characterize AzuR, we overexpressed it in Escherichia coli and purified it by chitin affinity chromatography. Far-UV circular dichroism spectroscopy indicated that the recombinant AzuR protein possessed a properly folded structure. Glutaraldehyde cross-linking and size-exclusion chromatography revealed that AzuR exists as a dimer of ∼28 kDa in solution. Analysis of its putative promoter region [100 bp upstream of nmtA open reading frame (ORF)] identified the presence of a 12–2–12 imperfect inverted repeat as the cis-acting element important for repressor binding. Electrophoretic mobility shift assays (EMSAs) showed concentration-dependent binding of recombinant dimeric AzuR with the promoter indicating that NmtA is indeed a regulatory target of AzuR. Binding of AzuR to DNA was disrupted in the presence of metal ions like Zn2+, Cd2+, Cu2+, Co2+, Ni2+, Pb2+, and Mn2+. The metal-dependent dissociation of protein–DNA complexes suggested the negative regulation of metal-inducible nmtA expression by AzuR. Overexpression of azuR in its native strain Anabaena 7120 enhanced the susceptibility to cadmium stress significantly. Overall, we propose a negative regulation of Anabaena MT by an α5 SmtB/ArsR metalloregulator AzuR.

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NmtA, a novel metallothionein of Anabaena sp. strain PCC 7120 imparts protection against cadmium stress but not oxidative stress

Cited by 21 publications

References 51 publications

Proteogenomic Analysis Provides Novel Insight into Genome Annotation and Nitrogen Metabolism in Nostoc sp. PCC 7120

Proteogenomic Analysis Provides Novel Insight into Genome Annotation and Nitrogen Metabolism in Nostoc sp. PCC 7120

Metallothionein 1: A New Spotlight on Inflammatory Diseases

AzuR From the SmtB/ArsR Family of Transcriptional Repressors Regulates Metallothionein in Anabaena sp. Strain PCC 7120

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