Chromate Binding and Removal by the Molybdate‐Binding Protein ModA

Karpus, Jason; Bosscher, Michael; Ajiboye, Ifedayo; Zhang, Liang; He, Chuan

doi:10.1002/cbic.201700051

Cited by 8 publications

(6 citation statements)

References 36 publications

(53 reference statements)

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“…Contradictory information is available on the binding of chromate to the E. coli ModA tungstate/molybdate binding protein. Whereas Rech et al found that it failed to bind even when tested at 2 mM [76], another study reported a chromate K D of approximately 100 nM [80]. Our data are thus in agreement with the latter study indicating that chromate is recognized by ModA in addition to molybdate and tungstate.…”

Section: Resultssupporting

confidence: 91%

Determination of Ligand Profiles for Pseudomonas aeruginosa Solute Binding Proteins

Fernández

Rico-Jiménez

Ortega

et al. 2019

IJMS

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Solute binding proteins (SBPs) form a heterogeneous protein family that is found in all kingdoms of life. In bacteria, the ligand-loaded forms bind to transmembrane transporters providing the substrate. We present here the SBP repertoire of Pseudomonas aeruginosa PAO1 that is composed of 98 proteins. Bioinformatic predictions indicate that many of these proteins have a redundant ligand profile such as 27 SBPs for proteinogenic amino acids, 13 proteins for spermidine/putrescine, or 9 proteins for quaternary amines. To assess the precision of these bioinformatic predictions, we have purified 17 SBPs that were subsequently submitted to high-throughput ligand screening approaches followed by isothermal titration calorimetry studies, resulting in the identification of ligands for 15 of them. Experimentation revealed that PA0222 was specific for γ-aminobutyrate (GABA), DppA2 for tripeptides, DppA3 for dipeptides, CysP for thiosulphate, OpuCC for betaine, and AotJ for arginine. Furthermore, RbsB bound D-ribose and D-allose, ModA bound molybdate, tungstate, and chromate, whereas AatJ recognized aspartate and glutamate. The majority of experimentally identified ligands were found to be chemoattractants. Data show that the ligand class recognized by SPBs can be predicted with confidence using bioinformatic methods, but experimental work is necessary to identify the precise ligand profile.Chemosensory signal transduction has been extensively studied in Escherichia coli [2] that has four chemoreceptors with a periplasmic ligand binding domain (LBD) and an aerotaxis receptor that senses signals in the cytosol. Chemoreceptors can be stimulated by direct signal binding to the LBD and/or by the recognition of signal loaded solute binding proteins (SBPs) [6]. Interestingly, all four E. coli chemoreceptors can be stimulated by SBP binding causing chemotaxis to sugars, dipeptides, and autoinducer-2 [7-10].Many other bacteria contain more chemoreceptors, which are mostly of unknown function [11,12], and significant efforts are being made by the scientific community to identify the ligands they recognize. Among the model organisms to study chemoreceptors is the human pathogen Pseudomonas aeruginosa PAO1 that has 26 chemoreceptor genes [13]. The functions of a significant number of P. aeruginosa chemoreceptors has been identified and receptors for amino acids and GABA [14,15], polyamines and histamine [16], nitrate [17], α-ketoglutarate [18], or inorganic phosphate [19,20] have been reported. However, screening experiments using ligand libraries have failed to identify ligands that bind to many other P. aeruginosa chemoreceptors. This may indicate that the ligand(s) is (are) not contained in the compound library used for screening or, alternatively, that the receptor is activated by the binding of signal-loaded SBPs. The abundance of SBP mediated chemoreceptor activation in E. coli, the failure to identify directly binding ligands for P. aeruginosa chemoreceptors and the evidence for SBP mediated chemoreceptor activation in other spec...

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Section: Resultssupporting

confidence: 91%

Determination of Ligand Profiles for Pseudomonas aeruginosa Solute Binding Proteins

Fernández

Rico-Jiménez

Ortega

et al. 2019

IJMS

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“…In addition, sericin has both hydrophilic and hydrophobic as well as positively and negatively charged residues, which may confer on it exceptional binding capacities for heavy metals and other pollutants via noncovalent interactions. Similarly, Karpus et al recently showed the specic binding of Cr(VI) ions by the molybdate-binding protein ModA, 34 and Kwak et al recently showed Cr(VI) removal with sericin beads. 35 Hence, the incorporation of proteins into composites with adsorbent materials might be a viable strategy to improve the adsorption capacities of the adsorbent materials, as well as create an insoluble adsorbent from two materials that are soluble in various aqueous media.…”

Section: Introductionmentioning

confidence: 91%

Hexavalent chromium ion and methyl orange dye uptake via a silk protein sericin–chitosan conjugate

et al. 2018

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“…For CrO, P. aeruginosa ModA had a K d value of 927.0 ± 87.7 nM, approximately 900-fold lower than MoO and WO ( Figure 1C ; Table 2 ). Thus, the relative affinity of P. aeruginosa PAO1 ModA for CrO is more similar to Bacillus strain EB106-08-02-XG196 ModA ( K d = 1.56 ± 0.5 μM; ~750-fold difference in affinity for CrO vs. MoO; Ge et al, 2020 ), than E. coli ( K d = 68–162 nM; ~2–4 fold difference in affinity for CrO vs. MoO; Karpus et al, 2017 ). Collectively, these data show that P. aeruginosa ModA has the capacity to interact with the oxyanions of group 6 metals and, notably, with greater affinity for MoO and WO than reported for orthologous ModA SBPs to date.…”

Section: Resultsmentioning

confidence: 91%

“…The result was a depletion in cellular Mo, with concomitant impacts on nitrate reductase activity and inhibition of anaerobic growth in WO-supplemented media ( Pederick et al, 2014 ). Recently, E. coli ModA was shown to also interact with chromate (CrO 4 2− ; henceforth CrO), the oxyanion form of the first group 6 element chromium (Cr), with a modest difference in relative affinity ( K d = ~68–162 nM) to MoO ( Karpus et al, 2017 ). Industrial use of chromium is widespread due to its favorable properties in the production of metal alloys, pigments, textile dyes, and applications in tanneries.…”

Section: Introductionmentioning

confidence: 99%

The Impact of Chromate on Pseudomonas aeruginosa Molybdenum Homeostasis

et al. 2022

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Acquisition of the trace-element molybdenum via the high-affinity ATP-binding cassette permease ModABC is essential for Pseudomonas aeruginosa respiration in anaerobic and microaerophilic environments. This study determined the X-ray crystal structures of the molybdenum-recruiting solute-binding protein ModA from P. aeruginosa PAO1 in the metal-free state and bound to the group 6 metal oxyanions molybdate, tungstate, and chromate. Pseudomonas aeruginosa PAO1 ModA has a non-contiguous dual-hinged bilobal structure with a single metal-binding site positioned between the two domains. Metal binding results in a 22° relative rotation of the two lobes with the oxyanions coordinated by four residues, that contribute six hydrogen bonds, distinct from ModA orthologues that feature an additional oxyanion-binding residue. Analysis of 485 Pseudomonas ModA sequences revealed conservation of the metal-binding residues and β-sheet structural elements, highlighting their contribution to protein structure and function. Despite the capacity of ModA to bind chromate, deletion of modA did not affect P. aeruginosa PAO1 sensitivity to chromate toxicity nor impact cellular accumulation of chromate. Exposure to sub-inhibitory concentrations of chromate broadly perturbed P. aeruginosa metal homeostasis and, unexpectedly, was associated with an increase in ModA-mediated molybdenum uptake. Elemental analyses of the proteome from anaerobically grown P. aeruginosa revealed that, despite the increase in cellular molybdenum upon chromate exposure, distribution of the metal within the proteome was substantially perturbed. This suggested that molybdoprotein cofactor acquisition may be disrupted, consistent with the potent toxicity of chromate under anaerobic conditions. Collectively, these data reveal a complex relationship between chromate toxicity, molybdenum homeostasis and anaerobic respiration.

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Chromate Binding and Removal by the Molybdate‐Binding Protein ModA

Cited by 8 publications

References 36 publications

Determination of Ligand Profiles for Pseudomonas aeruginosa Solute Binding Proteins

Determination of Ligand Profiles for Pseudomonas aeruginosa Solute Binding Proteins

Hexavalent chromium ion and methyl orange dye uptake via a silk protein sericin–chitosan conjugate

The Impact of Chromate on Pseudomonas aeruginosa Molybdenum Homeostasis

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