Microbial metabolism of reduced phosphorus compounds.
ABSTRACT The field of bacterial phosphorus (P) metabolism has undergone a significant transformation in the past decade owing to the elucidation of widespread and diverse pathways for the metabolism of reduced P compounds. The characterization of these pathways dramatically changes the current and narrow view of P metabolism and our understanding of the forms in which P is produced and available in the environment. In this review, recent investigations into the biochemical pathways and molecular genetics of reduced P metabolism in bacteria are discussed. Particular attention is paid to recently elucidated metabolic reactions and the genetic characterization of biosynthesis of organic reduced P compounds and to the pathways for oxidation of the inorganic reduced P compounds hypophosphite and phosphite.
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ABSTRACT: We report the draft genome sequence of Serratia sp. strain DD3, a gammaproteobacterium from the family Enterobacteriaceae. It was isolated from homogenized guts of Daphnia magna. The genome size is 5,274 Mb.Genome Announcements 09/2014; 2(5).
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ABSTRACT: PhnJ from the C-P lyase complex catalyzes the cleavage of the carbon-phosphorus bond in ribose-1-phosphonate-5-phosphate (PRPn) to produce methane and ribose-1,2-cyclic-phosphate-5-phosphate (PRcP). This protein is a novel radical SAM enzyme that uses glycyl and thiyl radicals as reactive intermediates in the proposed reaction mechanism. The overall reaction is initiated with the reductive cleavage of S-adenosylmethionine (SAM) by a reduced [4Fe-4S]1+-cluster to form an Ado-CH2∙ radical intermediate. This intermediate abstracts the proR hydrogen from Gly-32 of PhnJ to form Ado-CH3 and a glycyl radical. In the next step, there is hydrogen atom transfer from Cys-272 to the Gly-32 radical to generate a thiyl radical. The thiyl radical attacks the phosphorus center of the substrate, PRPn, to form a transient thiophosphonate radical intermediate. This intermediate collapses via homolytic C-P bond cleavage and hydrogen atom transfer from the proS hydrogen of Gly-32 to produce a thiophosphate intermediate, methane, and a radical intermediate at Gly-32. The final product, PRcP, is formed by nucleophilic attack of the C2-hydroxyl on the transient thiophosphate intermediate. This reaction regenerates the free thiol group of Cys-272. After hydrogen atom transfer from Cys-272 to the Gly-32 radical, the entire process is repeated with another substrate molecule without the use of another molecule of SAM or involvement from the [4Fe-4S]-cluster again.Perspectives in Science. 12/2014;
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ABSTRACT: The element phosphorus (P) controls growth in many ecosystems as the limiting nutrient, where it is broadly considered to reside as pentavalent P in phosphate minerals and organic esters. Exceptions to pentavalent P include phosphine-PH3-a trace atmospheric gas, and phosphite and hypophosphite, P anions that have been detected recently in lightning strikes, eutrophic lakes, geothermal springs, and termite hindguts. Reduced oxidation state P compounds include the phosphonates, characterized by C-P bonds, which bear up to 25% of total organic dissolved phosphorus. Reduced P compounds have been considered to be rare; however, the microbial ability to use reduced P compounds as sole P sources is ubiquitous. Here we show that between 10% and 20% of dissolved P bears a redox state of less than +5 in water samples from central Florida, on average, with some samples bearing almost as much reduced P as phosphate. If the quantity of reduced P observed in the water samples from Florida studied here is broadly characteristic of similar environments on the global scale, it accounts well for the concentration of atmospheric phosphine and provides a rationale for the ubiquity of phosphite utilization genes in nature. Phosphine is generated at a quantity consistent with thermodynamic equilibrium established by the disproportionation reaction of reduced P species. Comprising 10-20% of the total dissolved P inventory in Florida environments, reduced P compounds could hence be a critical part of the phosphorus biogeochemical cycle, and in turn may impact global carbon cycling and methanogenesis.Proceedings of the National Academy of Sciences 10/2014; · 9.81 Impact Factor