Benzo[a]pyrene might be transported by a TonB-dependent transporter in Novosphingobium pentaromativorans US6-1

Sphingomonads are well known for their ability to efficiently degrade polycyclic aromatic hydrocarbons (PAHs), but little is known about the mechanism of PAH uptake and transport across the cell membrane. RNA sequencing analysis of a sphingomonad, Novosphingobium pentaromativorans US6–1 showed that...

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Published in:Journal of hazardous materials 2021-02, Vol.404 (Pt A), p.124037-124037, Article 124037
Main Authors: Liang, Jiaqing, Xu, Jiantao, Zhao, Weijun, Wang, Jiaofeng, Chen, Kai, Li, Yuqian, Tian, Yun
Format: Article
Language:English
Subjects:
Benzo(a)pyrene - toxicity
Benzo[a]pyrene
Membrane Transport Proteins
Novosphingobium pentaromativorans US6–1
Polycyclic Aromatic Hydrocarbons - toxicity
Sphingomonadaceae - genetics
TonB-dependent transporters
Transport
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Summary:Sphingomonads are well known for their ability to efficiently degrade polycyclic aromatic hydrocarbons (PAHs), but little is known about the mechanism of PAH uptake and transport across the cell membrane. RNA sequencing analysis of a sphingomonad, Novosphingobium pentaromativorans US6–1 showed that 38 TonB-dependent transporter (TBDT) genes were significantly upregulated under 5-ring PAH-benzo[a]pyrene (BaP) stress. In order to reveal whether TBDTs are involved in uptake and transport BaP in US6–1, the key TBDT genes were deleted to generate mutants. The results showed that the growth status of these mutants was not different from that of the wild-type strains, but the PAH degradation ability decreased, especially for the mutant strain Δtbdt-11, which did not encode the tbdt-11 gene. Meanwhile, the cell surface hydrophobicity (CSH) of Δtbdt-11 was found to be significantly lower than that of the wild-type strain under BaP stress. Furthermore, the transcriptional activity of genes encoding PAH degradative enzymes was found to be greatly reduced in Δtbdt-11. Confocal microscopy observations showed that US6–1 could transport BaP across the outer membrane, but this transport capacity was significantly reduced in Δtbdt-11 and wild-type US6–1 treated with PMF uncoupler, further confirming that the tbdt-11 gene was associated with PAH active transport. [Display omitted] •TonB-dependent transport systems respond positively to the pressure of BaP in US6-1. •The TBDT gene tbdt-11 is responsible for the transportation of BaP in US6-1. •TBDT genes might be involved in regulating PAHs absorption and degradation in US6-1.
ISSN:0304-3894
1873-3336
DOI:10.1016/j.jhazmat.2020.124037