Functional Diversity of TonB-Like Proteins in the Heterocyst-Forming Cyanobacterium
            <i>Anabaena</i>
            sp. PCC 7120

Schätzle, Hannah; Arévalo, Sergio; Fresenborg, Leonard S.; Seitz, Hans-Michael; Flores, Enrique; Schleiff, Enrico

doi:10.1128/msphere.00214-21

Cited by 5 publications

(7 citation statements)

References 107 publications

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“…PCC7120 (previously Anabaena sp. PCC7120) (Schätzle et al, 2021), we focus on the deeply branching strain of Pseudanabaena sp. PCC7367.…”

Section: Introductionmentioning

confidence: 99%

“…The permease, cFTR1, takes up Fe(III) possibly by re‐oxidation of Fe(II) by oxygen (Xu et al, 2016). Potentially the TonB – ExbB/D complex coordinates with TBDTs to take up iron that is bound to organic ligands (Boukhalfa & Crumbliss, 2002; Jiang et al, 2015; Schätzle et al, 2021). ExbB/D was also found to take up inorganic iron directly (Jiang et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

“…7120 (Fresenborg et al, 2020). Furthermore, we screened for siderophore‐associated uptake genes encoding TBDTs, TonB, and the ExbB/D complex (Jiang et al, 2015; Qiu et al, 2018; Schätzle et al, 2021). The expression of cftr1 , the cytochrome c oxidase gene, cyoC , and the intracellular iron transcriptional regulator gene, furA , in cultures of Pseudanabaena sp.…”

Section: Introductionmentioning

confidence: 99%

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On the trail of iron uptake in ancestral Cyanobacteria on early Earth

et al. 2022

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Cyanobacteria oxygenated Earth's atmosphere ~2.4 billion years ago, during the Great Oxygenation Event (GOE), through oxygenic photosynthesis. Their high iron requirement was presumably met by high levels of Fe(II) in the anoxic Archean environment.We found that many deeply branching Cyanobacteria, including two Gloeobacter and four Pseudanabaena spp., cannot synthesize the Fe(II) specific transporter, FeoB.Phylogenetic and relaxed molecular clock analyses find evidence that FeoB and the Fe(III) transporters, cFTR1 and FutB, were present in Proterozoic, but not earlier Archaean lineages of Cyanobacteria. Furthermore Pseudanabaena sp. PCC7367, an early diverging marine, benthic strain grown under simulated Archean conditions, constitutively expressed cftr1, even after the addition of Fe(II). Our genetic profiling suggests that, prior to the GOE, ancestral Cyanobacteria may have utilized alternative metal iron transporters such as ZIP, NRAMP, or FicI, and possibly also scavenged exogenous siderophore bound Fe(III), as they only acquired the necessary Fe(II) and Fe(III) transporters during the Proterozoic. Given that Cyanobacteria arose 3.3-3.6 billion years ago, it is possible that limitations in iron uptake may have contributed to the delay in their expansion during the Archean, and hence the oxygenation of the early Earth.

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“…PCC7120 (previously Anabaena sp. PCC7120) (Schätzle et al, 2021), we focus on the deeply branching strain of Pseudanabaena sp. PCC7367.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On the trail of iron uptake in ancestral Cyanobacteria on early Earth

et al. 2022

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“…The involvement of TonB proteins in distinct functions other than iron acquisition has been reported, such as the involvement of P. aeruginosa TonB3 in twitching motility and type IV pili assembly ( Huang et al., 2004 ), S. maltophilia TonB1 in β-lactam susceptibility ( Calvopiña et al., 2020 ), and Anabaena sp. TonB2 in outer membrane integrity ( Schätzle et al., 2021 ). The hemP-hemA-Smlt0796-Smlt0797 operon is repressed by Fur in iron-replete conditions ( Figure 6A ).…”

Section: Discussionmentioning

confidence: 99%

HemU and TonB1 contribute to hemin acquisition in Stenotrophomonas maltophilia

Liao,

Lu,

Yang

et al. 2024

Front. Cell. Infect. Microbiol.

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IntroductionThe hemin acquisition system is composed of an outer membrane TonB-dependent transporter that internalizes hemin into the periplasm, periplasmic hemin-binding proteins to shuttle hemin, an inner membrane transporter that transports hemin into the cytoplasm, and cytoplasmic heme oxygenase to release iron. Fur and HemP are two known regulators involved in the regulation of hemin acquisition. The hemin acquisition system of Stenotrophomonas maltophilia is poorly understood, with the exception of HemA as a TonB-dependent transporter for hemin uptake.MethodsPutative candidates responsible for hemin acquisition were selected via a homolog search and a whole-genome survey of S. maltophilia. Operon verification was performed by reverse transcription-polymerase chain reaction. The involvement of candidate genes in hemin acquisition was assessed using an in-frame deletion mutant construct and iron utilization assays. The transcript levels of candidate genes were determined using quantitative polymerase chain reaction.ResultsSmlt3896-hemU-exbB2-exbD2-tonB2 and tonB1-exbB1-exbD1a-exbD1b operons were selected as candidates for hemin acquisition. Compared with the parental strain, hemU and tonB1 mutants displayed a defect in their ability to use hemin as the sole iron source for growth. However, hemin utilization by the Smlt3896 and tonB2 mutants was comparable to that of the parental strain. HemA expression was repressed by Fur in iron-replete conditions and derepressed in iron-depleted conditions. HemP negatively regulated hemA expression. Like hemA, hemU was repressed by Fur in iron-replete conditions; however, hemU was moderately derepressed in response to iron-depleted stress and fully derepressed when hemin was present. Unlike hemA and hemU, the TonB1-exbB1-exbD1a-exbD1b operon was constitutively expressed, regardless of the iron level or the presence of hemin, and Fur and HemP had no influence on its expression.ConclusionHemA, HemU, and TonB1 contribute to hemin acquisition in S. maltophilia. Fur represses the expression of hemA and hemU in iron-replete conditions. HemA expression is regulated by low iron levels, and HemP acts as a negative regulator of this regulatory circuit. HemU expression is regulated by low iron and hemin levels in a hemP-dependent manner.

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“…They perform the roles with TonB genes to transport the energy of the proton-motive force to outer membrane receptors in Serratia marcescens for the assimilation of iron. Schätzle et al (2021) also reported how these genes were produced by Pseudomonas putida WCS358 and involved in ferric-pseudobactin transport and siderophore production. fecR and pvdD genes that encode iron (III) dicitrate transmembrane sensor protein and pyoverdine sidechain non-ribosomal peptide synthetase were abundant in the HR.…”

Section: Discussionmentioning

confidence: 99%

Unraveling the functional genes present in rhizosphere microbiomes of Solanum lycopersicum

Adedayo¹,

Fadiji²,

Babalola³

2023

PeerJ

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The microbiomes living in the rhizosphere soil of the tomato plant contribute immensely to the state of health of the tomato plant alongside improving sustainable agriculture. With the aid of shotgun metagenomics sequencing, we characterized the putative functional genes (plant-growth-promoting and disease-resistant genes) produced by the microbial communities dwelling in the rhizosphere soil of healthy and powdery mildew-diseased tomato plants. The results identified twenty-one (21) plant growth promotion (PGP) genes in the microbiomes inhabiting the healthy rhizosphere (HR) which are more predomiant as compared to diseased rhizosphere (DR) that has nine (9) genes and four (4) genes in bulk soil (BR). Likewise, we identified some disease-resistant genes which include nucleotide binding genes and antimicrobial genes. Our study revealed fifteen (15) genes in HR which made it greater in comparison to DR that has three (3) genes and three (3) genes in bulk soil. Further studies should be conducted by isolating these microorganisms and introduce them to field experiments for cultivation of tomatoes.

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Functional Diversity of TonB-Like Proteins in the Heterocyst-Forming Cyanobacterium Anabaena sp. PCC 7120

Abstract: The genomes of many organisms encode more than one TonB protein, and their number does not necessarily correlate with that of TonB-dependent outer membrane transporters. Consequently, specific as well as redundant functions of the different TonB proteins have been identified.

Cited by 5 publications

References 107 publications

On the trail of iron uptake in ancestral Cyanobacteria on early Earth

On the trail of iron uptake in ancestral Cyanobacteria on early Earth

HemU and TonB1 contribute to hemin acquisition in Stenotrophomonas maltophilia

Unraveling the functional genes present in rhizosphere microbiomes of Solanum lycopersicum

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