Phototrophic N and CO Fixation Using a -H Mediated Electrochemical System With Infrared Photons.

A promising approach for the synthesis of high value reduced compounds is to couple bacteria to the cathode of an electrochemical cell, with delivery of electrons from the electrode driving reductive biosynthesis in the bacteria. Such systems have been used to reduce CO to acetate and other C-based compounds. Here, we report an electrosynthetic system that couples a diazotrophic, photoautotrophic bacterium, TIE-1, to the cathode of an electrochemical cell through the mediator H that allows reductive capture of both CO and N with all of the energy coming from the electrode and infrared (IR) photons.

Transcriptome differences in the rumen of beef steers with variation in feed intake and gain.

Background: Feed intake and gain are economically important traits in beef production. The rumen wall interacts with feed, microbial populations, and fermentation products important to cattle nutrition. As such, it is likely to be a critical component in the beef steer's ability to utilize feedstuffs efficiently.

50 years of the Wyoming ram test: How sheep have changed.

Production characteristics of white-faced rams have been systematically evaluated over a 140-d test in Wyoming since 1961. Individual test records ( = 4,240) from rams on test were analyzed to determine change over the past 52 yr. Although rams on test are not older, weight on and off test has increased ( < 0.

Catalytic mechanism of Golgi-resident human tyrosylprotein sulfotransferase-2: a mass spectrometry approach.

Human tyrosylprotein sulfotransferases catalyze the transfer of a sulfuryl moiety from the universal sulfate donor PAPS to the hydroxyl substituent of tyrosine residues in proteins and peptides to yield tyrosine sulfated products and PAP. Tyrosine sulfation occurs in the trans-Golgi network, affecting an estimated 1% of the tyrosine residues in all secreted and membrane-bound proteins in higher order eukaryotes. In this study, an effective LC-MS-based TPST kinetics assay was developed and utilized to measure the kinetic properties of human TPST-2 and investigate its catalytic mechanism when G protein-coupled CC-chemokine receptor 8 (CCR8) peptides were used as acceptor substrates.

Effect of subacute dietary nitrate on production traits and plasma analytes in Suffolk ewes.

Elevated dietary nitrate (NO3-) is associated with production losses in ruminant livestock, resulting in substantial economic losses incurred by producers. Severe drought, fertilization practices and poorly maintained pastures increase the risk of elevated NO3- intake among cattle and sheep. Nitrate is metabolized to nitrite (NO2-) in the rumen and further reduced to ammonia.

Effects of ruminal protein degradability and frequency of supplementation on site and extent of digestion and ruminal fermentation characteristics in lambs fed low-quality forage.

Four ruminally and duodenally cannulated Suffolk wether lambs (34.5 +/- 2.0 kg initial BW) were used in a 4 x 4 Latin square-designed experiment to examine the effects of ruminal protein degradability and supplementation frequency on site and extent of digestion in lambs consuming a low-quality forage diet.

Effects of ruminal protein degradability and frequency of supplementation on nitrogen retention, apparent digestibility, and nutrient flux across visceral tissues in lambs fed low-quality forage.

Two experiments were conducted to determine the effect of ruminal protein degradability and supplementation frequency on intake, apparent digestibility, N retention, and nutrient flux across visceral tissues of lambs fed a low-quality forage diet. In both experiments, wethers were fed a basal diet of mature crested wheatgrass hay (4.2% CP) for ad libitum consumption plus 1 of 4 supplements: 1) a high RDP supplement provided daily (RDP-D), 2) the high RDP supplement provided on alternate days (RDP-A), 3) a high RUP provided on alternate days (RUP-A), or 4) a 50:50 mixture of the RDP and RUP supplements provided on alternate days.

Growth and carcass fatty acid composition of beef steers fed soybean oil for increasing duration before slaughter.

Duration of soybean oil (SBO) supplementation needed to enhance carcass conjugated linoleic acid (CLA) and trans-vaccenic (TVA) content was examined using 96 beef steers (293.6±3.9kg) fed a 78% corn-based diet supplemented with SBO for 0, 77, 137, or 189days before slaughter.

Effect of protein supplementation on expression and distribution of urea transporter-B in lambs fed low-quality forage.

Two experiments were conducted to determine the effects of ruminal protein degradability, supplementation frequency, and increasing dietary protein on the expression and distribution of urea transporter-B (UT-B) in lambs fed low-quality forage (mature crested wheatgrass hay; 4.2 to 4.7% CP).

Biosynthesis of the iron-molybdenum cofactor of nitrogenase.

The iron-molybdenum cofactor (FeMo-co), located at the active site of the molybdenum nitrogenase, is one of the most complex metal cofactors known to date. During the past several years, an intensive effort has been made to purify the proteins involved in FeMo-co synthesis and incorporation into nitrogenase. This effort is starting to provide insights into the structures of the FeMo-co biosynthetic intermediates and into the biochemical details of FeMo-co synthesis.

Extended X-ray absorption fine structure and nuclear resonance vibrational spectroscopy reveal that NifB-co, a FeMo-co precursor, comprises a 6Fe core with an interstitial light atom.

NifB-co, an Fe-S cluster produced by the enzyme NifB, is an intermediate on the biosynthetic pathway to the iron molybdenum cofactor (FeMo-co) of nitrogenase. We have used Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy together with (57)Fe nuclear resonance vibrational spectroscopy (NRVS) to probe the structure of NifB-co while bound to the NifX protein from Azotobacter vinelandii. The spectra have been interpreted in part by comparison with data for the completed FeMo-co attached to the NafY carrier protein: the NafY:FeMo-co complex.

Effects of supplemental ruminally degradable protein versus increasing amounts of supplemental ruminally undegradable protein on site and extent of digestion and ruminal characteristics in lambs fed low-quality forage.

Four ruminally and duodenally cannulated Suffolk wether lambs (34.5 +/- 2 kg initial BW) were used in a 4 x 4 Latin square designed experiment to compare effects of supplemental ruminally degradable protein (RDP) vs. increasing amounts of supplemental ruminally undegradable protein (RUP) on ruminal characteristics and site and extent of digestion in lambs.

Effects of supplemental ruminally degradable protein versus increasing amounts of supplemental ruminally undegradable protein on nitrogen retention, apparent digestibility, and nutrient flux across visceral tissues in lambs fed low-quality forage.

Two experiments were conducted to determine effects of supplemental ruminally degradable protein (RDP) vs. increasing amounts of supplemental ruminally undegradable protein (RUP) on intake, apparent digestibility, N retention, and nutrient flux across visceral tissues in lambs fed low-quality forage. Lambs were fed a basal diet of crested wheatgrass hay (4.

NifX and NifEN exchange NifB cofactor and the VK-cluster, a newly isolated intermediate of the iron-molybdenum cofactor biosynthetic pathway.

The iron-molybdenum cofactor of nitrogenase (FeMo-co) is synthesized in a multistep process catalysed by several Nif proteins and is finally inserted into a pre-synthesized apo-dinitrogenase to generate mature dinitrogenase protein. The NifEN complex serves as scaffold for some steps of this synthesis, while NifX belongs to a family of small proteins that bind either FeMo-co precursors or FeMo-co during cofactor synthesis. In this work, the binding of FeMo-co precursors and their transfer between purified Azotobacter vinelandii NifX and NifEN proteins was studied to shed light on the role of NifX on FeMo-co synthesis.

CO-dependent H2 evolution by Rhodospirillum rubrum: role of CODH:CooF complex.

Upon exposure to CO during anaerobic growth, the purple phototrophic bacterium Rhodospirillum rubrum expresses a CO-oxidizing H(2) evolving enzymatic system. The CO-oxidizing enzyme, carbon monoxide dehydrogenase (CODH), has been purified and extensively characterized. However the electron transfer pathway from CODH to the CO-induced hydrogenase that evolves H(2) is not well understood.

NifB-dependent in vitro synthesis of the iron-molybdenum cofactor of nitrogenase.

Biological nitrogen fixation, an essential process of the biogeochemical nitrogen cycle that supports life on Earth, is catalyzed by the nitrogenase enzyme. The nitrogenase active site contains an iron and molybdenum cofactor (FeMo-co) composed of 7Fe-9S-Mo-homocitrate and one not-yet-identified atom, which probably is the most complex [Fe-S] cluster in nature. Here, we show the in vitro synthesis of FeMo-co from its simple constituents, Fe, S, Mo, and homocitrate.

New insights into the mechanism of nickel insertion into carbon monoxide dehydrogenase: analysis of Rhodospirillum rubrum carbon monoxide dehydrogenase variants with substituted ligands to the [Fe3S4] portion of the active-site C-cluster.

Carbon monoxide dehydrogenase (CODH) from Rhodospirillum rubrum catalyzes the oxidation of CO to CO2. A unique [NiFe4S4] cluster, known as the C-cluster, constitutes the active site of the enzyme. When grown in Ni-deficient medium R.

Nitrogen fixation by photosynthetic bacteria.

In 1949, Howard Gest and Martin Kamen published two brief papers in Science that changed our perceptions about the metabolic capabilities of photosynthetic bacteria. Their discovery of photoproduction of hydrogen and the ability of Rhodospirillum rubrum to fix nitrogen led to a greater understanding of both processes.

NAD-, NMN-, and NADP-dependent modification of dinitrogenase reductases from Rhodospirillum rubrum and Azotobacter vinelandii.

Nitrogenase activity in the photosynthetic bacterium Rhodospirillum rubrum is reversibly regulated by ADP-ribosylation of a specific arginine residue of dinitrogenase reductase based on the cellular nitrogen or energy status. In this paper, we have investigated the ability of nicotinamide adenine dinucleotide, NAD (the physiological ADP-ribose donor), and its analogs to support covalent modification of dinitrogenase reductase in vitro. R.

Supplementing a ruminally undegradable protein supplement to maintain essential amino acid supply to the small intestine when forage intake is restricted in beef cattle.

Twelve Angus crossbred cattle (eight heifers and four steers; average initial BW = 594 +/- 44.4 kg) fitted with ruminal and duodenal cannulas and fed restricted amounts of forage plus a ruminally undegradable protein (RUP) supplement were used in a triplicated 4 x 4 Latin square design experiment to determine intestinal supply of essential AA. Cattle were fed four different levels of chopped (2.

Effect of restricted forage intake on ruminal disappearance of bromegrass hay and a blood meal, feather meal, and fish meal supplement.

Two experiments were conducted to determine in situ disappearance of bromegrass hay and a ruminally undegraded protein (RUP) supplement in beef cattle fed restricted amounts of forage. Six Angus crossbred cattle (BW = 589 +/- 44.4 kg; three steers and three heifers) fitted with ruminal cannulas were fed chopped (2.

Genes required for rapid expression of nitrogenase activity in Azotobacter vinelandii.

Rnf proteins are proposed to form membrane-protein complexes involved in the reduction of target proteins such as the transcriptional regulator SoxR or the dinitrogenase reductase component of nitrogenase. In this work, we investigate the role of rnf genes in the nitrogen-fixing bacterium Azotobacter vinelandii. We show that A.

Site and extent of digestion and amino acid flow to the small intestine in beef cattle consuming limited amounts of forage.

Eight Angus x Gelbvieh heifers (445 +/- 74.5 kg) fitted with ruminal and duodenal cannulas were used in a 4 x 4 Latin square double double-crossover designed experiment to assess the effect of restricted forage intake on site and extent of digestion and flow of essential AA amino acids to the small intestine. Heifers were fed chopped (2.

Purification and characterization of NafY (apodinitrogenase gamma subunit) from Azotobacter vinelandii.

The formation of an active dinitrogenase requires the synthesis and the insertion of the iron-molybdenum cofactor (FeMo-co) into a presynthesized apodinitrogenase. In Azotobacter vinelandii, NafY (also known as gamma protein) has been proposed to be a FeMo-co insertase because of its ability to bind FeMo-co and apodinitrogenase. Here we report the purification and biochemical characterization of NafY and reach the following conclusions.