The multifarious roles of Tol-Pal in Gram-negative bacteria

Szczepaniak, Joanna; Press, Cara; Kleanthous, Colin

doi:10.1093/femsre/fuaa018

Cited by 70 publications

(72 citation statements)

References 159 publications

(264 reference statements)

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“…TolR and pal are two genes of the Tol-Pal system, and the transposon insertion of tolR and pal showed 8.8-and 10.6-fold decreased prodigiosin production, respectively. The Tol-Pal system plays important roles in cell division and phospholipid transport from the membrane of bacteria (Szczepaniak et al, 2020). It was found that different kinds of oils can significantly enhance prodigiosin production of many strains in the Serratia genus (Wei and Chen, 2005;Abdul Manas et al, 2020), including the S. marcescens FZSF02 strain, which was used in this study (Lin et al, 2019).…”

Section: Discussionmentioning

confidence: 99%

Identification of Essential Genes Associated With Prodigiosin Production in Serratia marcescens FZSF02

et al. 2021

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Prodigiosin is a promising secondary metabolite produced mainly by Serratia strains. To study the global regulatory mechanism of prodigiosin biosynthesis, a mutagenesis library containing 23,000 mutant clones was constructed with the EZ-Tn5 transposon, and 114 clones in the library showed altered prodigiosin production ability. For 37 of the 114 clones, transposon insertion occurred on the prodigiosin biosynthetic cluster genes; transposon inserted genes of the 77 clones belonged to 33 different outside prodigiosin biosynthetic cluster genes. These 33 genes can be divided into transcription-regulating genes, membrane protein-encoding genes, and metabolism enzyme-encoding genes. Most of the genes were newly reported to be involved in prodigiosin production. Transcriptional levels of the pigA gene were significantly downregulated in 22 mutants with different inserted genes, which was in accordance with the phenotype of decreased prodigiosin production. Functional confirmation of the mutant genes involved in the pyrimidine nucleotide biosynthesis pathway was carried out by adding orotate and uridylate (UMP) into the medium. Gene complementation confirmed the regulatory function of the EnvZ/OmpR two-component regulatory system genes envZ and ompR in prodigiosin production.

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Section: Discussionmentioning

confidence: 99%

Identification of Essential Genes Associated With Prodigiosin Production in Serratia marcescens FZSF02

et al. 2021

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“…S3), which plays essential roles in the stabilization of the outer membrane structure and septum formation during cell division. Additionary, ybgC, whose relevance to the Tol-Pal system is unknown, was found immediately upstream of exbB2/tolQ 19,28 . Since a similar set of genes (ybgC-tolQ-tolR-tolA-tolB-pal) has been found in many bacteria as the genes encoding the Tol-Pal system 29 , exbB2/tolQ and exbD3/tolR are likely components of the Tol-Pal system.…”

Section: Resultsmentioning

confidence: 99%

Functional roles of multiple Ton complex genes in a Sphingobium degrader of lignin-derived aromatic compounds

Fujita

Yano

Shibata

et al. 2021

Preprint

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TonB-dependent transporters (TBDTs) mediate outer membrane transport of nutrients using the energy derived from proton motive force transmitted from the TonB−ExbB−ExbD complex localized in the inner membrane. Recently, we discovered ddvT encoding a TBDT responsible for the uptake of a 5,5-type lignin-derived dimer in Sphingobium sp. strain SYK-6. Furthermore, overexpression of ddvT in an SYK-6-derivative strain enhanced its uptake capacity, improving the rate of platform chemical production. Thus, understanding the uptake system of lignin-derived aromatics is fundamental for microbial conversion-based lignin valorization. Here we examined whether multiple tonB-, exbB-, and exbD-like genes in SYK-6 contribute to the outer membrane transport of lignin-derived aromatics. The disruption of tonB2−6 and exbB3 did not reduce the capacity of SYK-6 to convert or grow on lignin-derived aromatics. In contrast, the introduction of the tonB1−exbB1−exbD1−exbD2 operon genes into SYK-6, which could not be disrupted, promoted the conversion of β-O-4-, β-5-, β-1-, β-β-, and 5,5-type dimers and monomers, such as ferulate, vanillate, syringate, and protocatechuate. These results suggest that TonB-dependent uptake involving the tonB1 operon genes is responsible for the outer membrane transport of the above aromatics. Additionally, exbB2/tolQ and exbD3/tolR were suggested to constitute the Tol-Pal system that maintains the outer membrane integrity.

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“…Their import is driven by the proton-motive force (PMF) in conjunction with either the Tol (group A bacteriocins) or the Ton (group B bacteriocins) systems 8 . The physiological roles of the Tol (also known as Tol-Pal) and Ton systems are to stabilise the OM during cell division 9 and transport nutrients through TonB-dependent transporters (TBDTs) 10 , respectively. These functions are parasitized by bacteriocins to catalyse their transfer across the OM.…”

Section: Introductionmentioning

confidence: 99%

Toxin import through the antibiotic efflux channel TolC

et al. 2021

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Bacteria often secrete diffusible protein toxins (bacteriocins) to kill bystander cells during interbacterial competition. Here, we use biochemical, biophysical and structural analyses to show how a bacteriocin exploits TolC, a major outer-membrane antibiotic efflux channel in Gram-negative bacteria, to transport itself across the outer membrane of target cells. Klebicin C (KlebC), a rRNase toxin produced by Klebsiella pneumoniae, binds TolC of a related species (K. quasipneumoniae) with high affinity through an N-terminal, elongated helical hairpin domain common amongst bacteriocins. The KlebC helical hairpin opens like a switchblade to bind TolC. A cryo-EM structure of this partially translocated state, at 3.1 Å resolution, reveals that KlebC associates along the length of the TolC channel. Thereafter, the unstructured N-terminus of KlebC protrudes beyond the TolC iris, presenting a TonB-box sequence to the periplasm. Association with proton-motive force-linked TonB in the inner membrane drives toxin import through the channel. Finally, we demonstrate that KlebC binding to TolC blocks drug efflux from bacteria. Our results indicate that TolC, in addition to its known role in antibiotic export, can function as a protein import channel for bacteriocins.

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The multifarious roles of Tol-Pal in Gram-negative bacteria

Cited by 70 publications

References 159 publications

Identification of Essential Genes Associated With Prodigiosin Production in Serratia marcescens FZSF02

Identification of Essential Genes Associated With Prodigiosin Production in Serratia marcescens FZSF02

Functional roles of multiple Ton complex genes in a Sphingobium degrader of lignin-derived aromatic compounds

Toxin import through the antibiotic efflux channel TolC

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