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Lead Resistance Mechanisms in Bacteria and Co-Selection to other Metals and Antibiotics
Published in Edgardo R. Donati, Heavy Metals in the Environment, 2018
Milind Mohan Naik, Lakshangy S. Charya, Pranaya Santosh Fadte
Three major families of efflux transporters involved in Zn2+/Cd2+/Pb2+resistance include: (1) P-type ATPase, e.g., the Cu(II), Pb(II), Cd(II), and Zn(II) ATPases of Gram-negative bacteria, (2) cation diffusion facilitator (CDF) and (3) CBA. CBA transporters are three-component trans-envelope pumps of Gram negative bacteria that operate as chemiosmotic antiporters. The three-component divalent-cation efflux systems cnr, ncc, and czc of Ralstonia metallidurans (formerly Alcaligenes eutrophus CH34) (Borremans et al., 2001). Cation diffusion facilitator (CDF) family transporters act as chemiosmotic ion-proton exchangers. P-type ATPases and CDF transporters export metal ions from the cytoplasm to the periplasm; whereas CBA transporters chiefly detoxify periplasmic metals (outer membrane efflux), i.e., CBA transporters further eliminate periplasmic ions transported there by ATPases or CDF transporters, a way before ions enter the cytoplasm. P-type ATPases and CDF transporters can functionally substitute each other but they cannot substitute CBA transporter and vice versa (Hynninen et al., 2009; Hynninen, 2010).
Omics Reflection on the Bacterial Escape from the Toxic Trap of Metal(loid)s
Published in Vineet Kumar, Vinod Kumar Garg, Sunil Kumar, Jayanta Kumar Biswas, Omics for Environmental Engineering and Microbiology Systems, 2023
Jayanta Kumar Biswas, Monojit Mondal, Vineet Kumar, Meththika Vithanage, Rangabhashiyam Selvasembian, Balram Ambade, Manish Kumar
The three additional efflux pump classes are chemiosmotic ion/proton exchangers: (3) the single membrane polypeptides of the major facilitator superfamily (MFS; generally a single polypeptide) that transverses the membrane 12 or 14 times primarily in an alpha helical structure (Saier et al. 1999); (4) the cation diffusion facilitator (CDF) family (including CzcD for cadmium, zinc, and cobalt) (Haney et al. 2005); and (5) the CBA family of three polypeptide chemiosmotic antiporters such as CzcCBA with an inner membrane (A) protein of over 1000 amino acids in length and an outer membrane (C) protein and a coupling (B) protein connecting the two in the periplasmic space.
Bacterial-Assisted Phytoextraction Mechanism of Heavy Metals by Native Hyperaccumulator Plants from Distillery Waste–Contaminated Site for Eco-restoration
Published in Ram Chandra, R.C. Sobti, Microbes for Sustainable Development and Bioremediation, 2019
Access of HMs to bare roots is confined to the first few millimeters of the root tip. Uptake and transport across root cellular membrane is an important process, which initiates metal absorption into plant tissues. Two different uptake routes have been reported: (i) passive uptake (apoplastic) driven only by the concentration gradient across the membrane and (ii) active uptake (symplastic) inducible substrate-specific and energy-dependent uptake mediated by membrane protein with transport functions. Either through passive or active uptake, root cells capture metals from soil that remain bound by their cell wall and then transported across the membrane. But the electrical charge on metal ions prevents their diffusion freely across the lipophilic cellular membranes into the cytosol. Therefore, metal transport into cells is also driven by ATP-dependent protein pumps that catalize H+ extrusion across the membrane. In the apoplastic pathway, metal ions or metal-chelate complexes enter roots through intercellular spaces. In contrast, the symplastic pathway is an energy-dependent process that is mediated by specific or generic metal ion carriers or channels. In the symplastic pathway, nonessential metal ions compete for the transmembrane carrier used by essential trace elements. For example, Ni and Cd compete for the transmembrane carrier used by Cu and Zn. Even metal chelates, such as Fe-phytosiderophore complexes, can be transported by the symplastic pathway. Transporter proteins and an intracellular high-affinity binding site mediate the uptake of metals across the root cell plasma membrane. Several classes of protein families, including the cation diffusion facilitator (CDF), zinc-iron permease (ZIP), CPx-type ATPases, and Nramp familes, have been implicated in HMs transport in plants (Yang et al. 2005).
Nanotoxicity modelling and removal efficiencies of ZnONP
Published in International Journal of Phytoremediation, 2018
Şeyda Fikirdeşici Ergen, Esra Üçüncü Tunca
The cation diffusion facilitator (CDF) family, which can be seen in eukaryotes, archaea and bacteriums, is known as metal tolerance proteins (MTP) and CDF transports the metals Zn, Mn, Fe, Ni, Cd out of the cell or to the vacuoles (Chen et al.2009; Kim et al.2004). In absence of some metals, transporters can provide the transportation of chemically same ions. In addition, there may occur a competition between the metals transported by same transporters. By the help of such many transport pathways and transporters, the uptaken amount of Zn in the medium is increased.
Lemna minor, a hyperaccumulator shows elevated levels of Cd accumulation and genomic template stability in binary application of Cd and Ni: a physiological and genetic approach
Published in International Journal of Phytoremediation, 2021
Ibrahim Ilker Ozyigit, Lutfi Arda, Bestenur Yalcin, Ibrahim Ertugrul Yalcin, Bihter Ucar, Asli Hocaoglu-Ozyigit
A number of transport proteins including CPx-type ATPases play a crucial role in heavy metal transport in terms of providing metal ion homeostasis in higher plants and also are important in endowing with heavy metal tolerance in which the copper transporters (CTR) natural resistance linked macrophage protein family (NRAMP) and cation diffusion facilitator (CDF) family are the two examples taken in charge (Ghori et al.2019; Ozyigit et al.2021). The transport of various cations including Cd, Fe, Mn, and Zn are carried out via several transporters belonging to ZIP gene family (Guerinot 2000).
From phytoremediation of soil contaminants to phytomanagement of ecosystem services in metal contaminated sites
Published in International Journal of Phytoremediation, 2018
Aritz Burges, Itziar Alkorta, Lur Epelde, Carlos Garbisu
A variety of physiological mechanisms underlies the unique characteristics of hyperaccumulators: Metal mobilization, through rhizosphere acidification or exudation of mobilizing compounds (Raskin et al.1997). Microorganisms in the rhizosphere of hyperaccumulators, including root-colonizing bacteria and mycorrhiza, appear to have a role in metal mobilization and availability. Whiting et al. (2001) found that rhizosphere acidification by microorganisms enhanced Zn bioavailability and accumulation in N. caerulescens. The secretion of chelates into the rhizosphere, frequently mediated by microorganisms, and subsequent uptake of the metal-chelate complexes has been described to facilitate metal mobilization by plants (Clemens et al.2002).Detoxification, through chelation inside the plant and vacuolar compartmentalization (Wu et al.2010). Chelation with certain ligands (e.g., malate, histidine, citrate, nicotinamine) routes metals to the xylem, promoting root-to-shoot translocation; in turn, phytochelatins and metallothioneins route metals toward intracellular sequestration in organelles (Clemens et al.2002; Eapen and D'Souza 2005).Transporter proteins, associated with the uptake, intracellular sequestration, and redistribution of metals in plants, e.g. the CPx-type metal ATPases, the natural resistance-associated macrophage (Nramp) proteins, the cation diffusion facilitator (CDF) family proteins, and the zinc-iron permease (ZIP) transporter proteins (Pence et al.2000; Williams et al.2000; Assunção et al.2001; Lombi et al.2002a). Genes encoding for ZIP transporters have been identified in Arabidopsis thaliana (Grotz et al.1998). In N. caerulescens, genes of the ZIP family were identified and cloned (ZNT1, ZNT2, and ZTP1); interestingly, these genes are highly expressed in N. caerulescens root tissues, whereas in the non-accumulator Thlaspi arvense these genes are expressed only under Zn deficiency (Pence et al.2000; Assunção et al.2001), suggesting that an alteration in the Zn-induced transcriptional downregulation of Zn transporter genes can play a role in Zn uptake and hyperaccumulation in N. caerulescens plants.