4 research outputs found
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Draft Genome Sequence of the Caffeine-Degrading Methylotroph Methylorubrum populi Pinkel.
A pink-pigmented facultative methylotroph, Methylorubrum populi Pinkel, was isolated from compost by selective enrichment with caffeine (3,5,7-trimethylxanthine) as the sole carbon, nitrogen, and energy source. We report here its high-quality draft genome sequence, assembled in 35 contigs totaling 5,630,907 bp. We identified 5,681 protein-coding sequences, including those putatively involved in caffeine degradation
Gene products and processes contributing to lanthanide homeostasis and methanol metabolism in \u3cem\u3eMethylorubrum extorquens\u3c/em\u3e AM1
Lanthanide elements have been recently recognized as “new life metals” yet much remains unknown regarding lanthanide acquisition and homeostasis. In Methylorubrum extorquens AM1, the periplasmic lanthanide-dependent methanol dehydrogenase XoxF1 produces formaldehyde, which is lethal if allowed to accumulate. This property enabled a transposon mutagenesis study and growth studies to confirm novel gene products required for XoxF1 function. The identified genes encode an MxaD homolog, an ABC-type transporter, an aminopeptidase, a putative homospermidine synthase, and two genes of unknown function annotated as orf6 and orf7. Lanthanide transport and trafficking genes were also identified. Growth and lanthanide uptake were measured using strains lacking individual lanthanide transport cluster genes, and transmission electron microscopy was used to visualize lanthanide localization. We corroborated previous reports that a TonB-ABC transport system is required for lanthanide incorporation to the cytoplasm. However, cells were able to acclimate over time and bypass the requirement for the TonB outer membrane transporter to allow expression of xoxF1 and growth. Transcriptional reporter fusions show that excess lanthanides repress the gene encoding the TonB-receptor. Using growth studies along with energy dispersive X-ray spectroscopy and transmission electron microscopy, we demonstrate that lanthanides are stored as cytoplasmic inclusions that resemble polyphosphate granules
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Chemotaxis of Pseudomonas putida F1 to Alcohols Is Mediated by the Carboxylic Acid Receptor McfP.
Although alcohols are toxic to many microorganisms, they are good carbon and energy sources for some bacteria, including many pseudomonads. However, most studies that have examined chemosensory responses to alcohols have reported that alcohols are sensed as repellents, which is consistent with their toxic properties. In this study, we examined the chemotaxis of Pseudomonas putida strain F1 to n-alcohols with chain lengths of 1 to 12 carbons. P. putida F1 was attracted to all n-alcohols that served as growth substrates (C2 to C12) for the strain, and the responses were induced when cells were grown in the presence of alcohols. By assaying mutant strains lacking single or multiple methyl-accepting chemotaxis proteins, the receptor mediating the response to C2 to C12 alcohols was identified as McfP, the ortholog of the P. putida strain KT2440 receptor for C2 and C3 carboxylic acids. Besides being a requirement for the response to n-alcohols, McfP was required for the response of P. putida F1 to pyruvate, l-lactate, acetate, and propionate, which are detected by the KT2440 receptor, and the medium- and long-chain carboxylic acids hexanoic acid and dodecanoic acid. β-Galactosidase assays of P. putida F1 carrying an mcfP-lacZ transcriptional fusion showed that the mcfP gene is not induced in response to alcohols. Together, our results are consistent with the idea that the carboxylic acids generated from the oxidation of alcohols are the actual attractants sensed by McfP in P. putida F1, rather than the alcohols themselves.IMPORTANCE Alcohols, released as fermentation products and produced as intermediates in the catabolism of many organic compounds, including hydrocarbons and fatty acids, are common components of the microbial food web in soil and sediments. Although they serve as good carbon and energy sources for many soil bacteria, alcohols have primarily been reported to be repellents rather than attractants for motile bacteria. Little is known about how alcohols are sensed by microbes in the environment. We report here that catabolizable n-alcohols with linear chains of up to 12 carbons serve as attractants for the soil bacterium Pseudomonas putida, and rather than being detected directly, alcohols appear to be catabolized to acetate, which is then sensed by a specific cell-surface chemoreceptor protein
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Gene products and processes contributing to lanthanide homeostasis and methanol metabolism in Methylorubrum extorquens AM1.
Lanthanide elements have been recently recognized as "new life metals" yet much remains unknown regarding lanthanide acquisition and homeostasis. In Methylorubrum extorquens AM1, the periplasmic lanthanide-dependent methanol dehydrogenase XoxF1 produces formaldehyde, which is lethal if allowed to accumulate. This property enabled a transposon mutagenesis study and growth studies to confirm novel gene products required for XoxF1 function. The identified genes encode an MxaD homolog, an ABC-type transporter, an aminopeptidase, a putative homospermidine synthase, and two genes of unknown function annotated as orf6 and orf7. Lanthanide transport and trafficking genes were also identified. Growth and lanthanide uptake were measured using strains lacking individual lanthanide transport cluster genes, and transmission electron microscopy was used to visualize lanthanide localization. We corroborated previous reports that a TonB-ABC transport system is required for lanthanide incorporation to the cytoplasm. However, cells were able to acclimate over time and bypass the requirement for the TonB outer membrane transporter to allow expression of xoxF1 and growth. Transcriptional reporter fusions show that excess lanthanides repress the gene encoding the TonB-receptor. Using growth studies along with energy dispersive X-ray spectroscopy and transmission electron microscopy, we demonstrate that lanthanides are stored as cytoplasmic inclusions that resemble polyphosphate granules