Finding novel chemoreceptors that specifically sense and trigger chemotaxis toward polycyclic aromatic hydrocarbons in Novosphingobium pentaromativorans US6-1

• Published in: Journal of hazardous materials Vol. 416; p. 126246
• Main Authors: Li, Yuqian, Liang, Jiaqing, Yang, Shuyue, Yao, Jiebin, Chen, Kai, Yang, Luxi, Zheng, Wei, Tian, Yun
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.08.2021
• Subjects: Chemotaxis; Methyl-accepting chemotaxis proteins (MCPs); Novosphingobium pentaromativorans US6-1; Polycyclic aromatic hydrocarbons (PAHs); Methyl-accepting chemotaxis proteins (MCPs); Novosphingobium pentaromativorans US6-1; Polycyclic aromatic hydrocarbons (PAHs); Chemotaxis
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2021.126246

Bacterial chemotaxis can improve the efficiency of aromatic compound degradation, however, knowledge of how bacteria sense high-molecular-weight polycyclic aromatic hydrocarbons (HMW-PAHs), is limited. Here, the chemotactic responses of Novosphingobium pentaromativorans US6-1 to 9 aromatic compounds were investigated. The results showed that US6-1 chemotactically responded to phenanthrene (PHE), pyrene (PYR), benzo[a]pyrene (BaP) and their six metabolites. Six methyl-accepting chemotaxis proteins (MCPs) were annotated from US6-1 genome, four of which contained putative ligand-binding domains (LBDs). To confirm whether these four MCPs were involved in triggering chemotaxis toward PAHs, the MCP mutants were constructed. Observations showed a loss of the chemotactic responses to benzoate, phthalate, PHE and BaP only in the mutant ∆mcp03030. Surface plasmon resonance (SPR) assays further confirmed that MCP03030LBD specifically bound phthalate, PHE, PYR and BaP, while MCP18870LBD bound only PYR. The mutant ∆mcp03030-∆mcp18870 was then constructed and was shown to have lost the chemotactic response to 5 aromatic compounds. Combined with the effects of outer membrane transporter deletion on chemotaxis and MCP deletion on the PAH degradation, our study demonstrated that the chemoreceptors MCP03030 and MCP18870 can recognize PAHs and their metabolites in the periplasm, triggering metabolism-dependent and metabolism-independent chemotaxis, and be linked with HMW-PAH biodegradation. [Display omitted] •The chemoreceptor MCP03030 specifically senses and binds PHE, BaP and the metabolite phthalate.•Chemoreceptors MCP03030 and MCP18870 jointly trigger chemotaxis toward pyrene in US6-1.•Chemotaxis toward PAHs can be metabolism-dependent and metabolism-independent in US6-1.•The sensing of PAHs in periplasm can be promoted by PAH transporters and link PAH degradation.