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Peter Nockemann

Publications and source records attributed to Peter Nockemann.

9 recordsLinked to original sources
PubMed2025

Diversity and distribution of the lanthanome in aerobic methane-oxidising bacteria.

BACKGROUND: Lanthanides (Ln) play important and often regulatory roles in the metabolism of methylotrophs, including methanotrophs, particularly through their involvement in methanol oxidation. However, the diversity, distribution, and ecological relevance of Ln-associated proteins (the lanthanome) in aerobic methane-oxidising bacteria (MOB) remain underexplored. This study investigates the lanthanome using genome, plasmid, and proteome data, alongside metatranscriptome data from methane-rich lake sediments. RESULTS: We surveyed 179 genomes spanning Proteobacterial, Verrucomicrobial, and Actinobacterial MOBs to examine the distribution of Ln-dependent methanol dehydrogenases (MDHs) and Ln transport proteins. Distinct lineage-specific patterns were observed: XoxF5 was the most widespread MDH variant in Proteobacteria, while XoxF2 was restricted to Verrucomicrobia. Transporter systems also showed distinct patterns, with LanM restricted to Alphaproteobacteria, LanPepSY and LanA confined to Gammaproteobacteria, and LutH-like receptors broadly distributed across all lineages. Homologues of these genes were also detected on plasmids, indicating potential for horizontal gene transfer. In Lake Washington sediment metatranscriptomes, lanthanome transcripts were detected, with Proteobacteria as dominant contributors. Notably, a large fraction of xoxF transcripts were affiliated with non-MOB Methylophilaceae, consistent with known cooperative interactions with MOB. Using Methylosinus trichosporium OB3b as a model, we assessed methane oxidation and proteomic responses to soluble CeCl3 and a mixed-lanthanide ore. Lag phases were prolonged in the presence of lanthanides, particularly with ore, but methane oxidation rates converged across treatments after acclimation. Proteomic analysis revealed extensive condition-specific responses, with 724 proteins differentially expressed in Ore treatment compared to 60 under CeCl3. XoxF3 and XoxF5 were upregulated while MxaF and its accessory proteins were downregulated, consistent with the "lanthanide switch". Notably, LanM was not expressed despite being encoded, whereas LutH-like receptor was downregulated under both treatments, likely reflecting regulatory control to prevent excess metal uptake. Additional upregulation of a TonB-dependent receptor and ABC transporter suggests a potential lanthanophore-mediated uptake strategy. CONCLUSION: This study highlights the diversity and ecological activity of Ln-binding and transport systems in MOBs, their plasmid localisation and potential mobility, and their distinct regulation under different Ln sources. The strong proteomic response to complex ore underscores the physiological flexibility of MOBs in coping with natural lanthanide forms. These findings provide a framework for ecological studies and candidate targets for biotechnological applications in methane bioconversion and sustainable lanthanide recovery from complex materials.

Horizontal gene transfer↗
PubMed2006

Visible-light-sensitized near-infrared luminescence from rare-earth complexes of the 9-hydroxyphenalen-1-one ligand.

The unique absorption properties of the 9-hydroxyphenalen-1-one (HPHN) ligand have been exploited to obtain visible-light-sensitizable rare-earth complexes in 1:3 and 1:4 metal-to-ligand ratios. In both stoichiometries (1:3, tris, Ln(PHN)3; 1:4, tetrakis, A[Ln(PHN)4], with Ln being a trivalent rare-earth ion and A being a monovalent cation), the complexes of Nd(III), Er(III), and Yb(III) show typical near-infrared luminescence upon excitation with visible light with wavelengths up to 475 nm. The X-ray crystal structures of the tris complexes show solvent coordination to the central rare-earth ion, whereas in the tetrakis complexes, the four PHN- ligands form a protective shield around the central ion, preventing small solvent molecules from coordinating to the rare-earth ion, at least in the solid state.

Journal Article↗
PubMed2006

Task-specific ionic liquid for solubilizing metal oxides.

Protonated betaine bis(trifluoromethylsulfonyl)imide is an ionic liquid with the ability to dissolve large quantities of metal oxides. This metal-solubilizing power is selective. Soluble are oxides of the trivalent rare earths, uranium(VI) oxide, zinc(II) oxide, cadmium(II) oxide, mercury(II) oxide, nickel(II) oxide, copper(II) oxide, palladium(II) oxide, lead(II) oxide, manganese(II) oxide, and silver(I) oxide. Insoluble or very poorly soluble are iron(III), manganese(IV), and cobalt oxides, as well as aluminum oxide and silicon dioxide. The metals can be stripped from the ionic liquid by treatment of the ionic liquid with an acidic aqueous solution. After transfer of the metal ions to the aqueous phase, the ionic liquid can be recycled for reuse. Betainium bis(trifluoromethylsulfonyl)imide forms one phase with water at high temperatures, whereas phase separation occurs below 55.5 degrees C (temperature switch behavior). The mixtures of the ionic liquid with water also show a pH-dependent phase behavior: two phases occur at low pH, whereas one phase is present under neutral or alkaline conditions. The structures, the energetics, and the charge distribution of the betaine cation and the bis(trifluoromethylsulfonyl)imide anion, as well as the cation-anion pairs, were studied by density functional theory calculations.

Conservation of Natural Resources↗
PubMed2005

Relaxometric study of copper [15]metallacrown-5 gadolinium complexes derived from alpha-aminohydroxamic acids.

Proton nuclear magnetic relaxation dispersion (NMRD) profiles were recorded between 0.24 mT and 1.4 T for lanthanum(III)- and gadolinium(III)-containing [15]metallacrown-5 complexes derived from alpha-aminohydroxamic acids and with copper(II) as the ring metal. The influence of the different R-groups on the proton relaxivity was investigated, and a linear relationship between the relaxivity and the molecular mass of the metallacrown complex was found. The selectivity of the metallacrown complexes was tested by transmetalation experiments with zinc(II) ions. The crystal structure of the copper [15]metallacrown-5 gadolinium complex with glycine hydroximate ligands is reported.

Copper↗
PubMed2005

Long-lived near-infrared luminescent lanthanide complexes of imidodiphosphinate "shell" ligands.

Near-infrared emitting complexes of Nd(III), Er(III), and Yb(III) based on hexacoordinate lanthanide ions with an aryl functionalized imidodiphosphinate ligand, tpip, have been synthesized and fully characterized. Three tpip ligands form a shell around the lanthanide with the ligand coordinating via the two oxygens leading to neutral complexes, Ln(tpip)3. In the X-ray crystal structures of Er(III) and Nd(III) complexes there is evidence of CH-pi interactions between the phenyl groups. Photophysical investigations of solution samples of the complexes demonstrate that all complexes exhibit relatively long luminescence lifetimes in nondeuteurated solvents. Luminescence studies of powder samples have also been recorded for examination of the properties of NIR complexes in the solid state for potential material applications. The results underline the effective shielding of the lanthanide by the twelve phenyl groups of the tpip ligands and the reduction of high-energy vibrations in close proximity to the lanthanide, both features important in the design of NIR emitting lanthanide complexes.

Diphosphonates↗
PubMed2004

Rare-earth quinolinates: infrared-emitting molecular materials with a rich structural chemistry.

Near-infrared-emitting rare-earth chelates based on 8-hydroxyquinoline have appeared frequently in recent literature, because they are promising candidates for active components in near-infrared-luminescent optical devices, such as optical amplifiers, organic light-emitting diodes, .... Unfortunately, the absence of a full structural investigation of these rare-earth quinolinates is hampering the further development of rare-earth quinolinate based materials, because the luminescence output cannot be related to the structural properties. After an elaborate structural elucidation of the rare-earth quinolinate chemistry we can conclude that basically three types of structures can be formed, depending on the reaction conditions: tris complexes, corresponding to a 1:3 metal-to-ligand ratio, tetrakis complexes, corresponding to a 1:4 metal-to-ligand ratio, and trimeric complexes, with a 3:8 metal-to-ligand ratio. The intensity of the emitted near-infrared luminescence of the erbium(III) complexes is highest for the tetrakis complexes of the dihalogenated 8-hydroxyquinolinates.

Journal Article↗