Ronald Claxton

Bio: Ronald Claxton is an academic researcher from University of Georgia. The author has contributed to research in topics: Biomass & Glutaredoxin. The author has an hindex of 4, co-authored 4 publications receiving 1103 citations.

Chloroplast monothiol glutaredoxins as scaffold proteins for the assembly and delivery of [2Fe–2S] clusters

Abstract: Glutaredoxins (Grxs) are small oxidoreductases that reduce disulphide bonds or protein-glutathione mixed disulphides. More than 30 distinct grx genes are expressed in higher plants, but little is currently known concerning their functional diversity. This study presents biochemical and spectroscopic evidence for incorporation of a [2Fe–2S] cluster in two heterologously expressed chloroplastic Grxs, GrxS14 and GrxS16, and in vitro cysteine desulphurase-mediated assembly of an identical [2Fe–2S] cluster in apo-GrxS14. These Grxs possess the same monothiol CGFS active site as yeast Grx5 and both were able to complement a yeast grx5 mutant defective in Fe–S cluster assembly. In vitro kinetic studies monitored by CD spectroscopy indicate that [2Fe–2S] clusters on GrxS14 are rapidly and quantitatively transferred to apo chloroplast ferredoxin. These data demonstrate that chloroplast CGFS Grxs have the potential to function as scaffold proteins for the assembly of [2Fe–2S] clusters that can be transferred intact to physiologically relevant acceptor proteins. Alternatively, they may function in the storage and/or delivery of preformed Fe–S clusters or in the regulation of the chloroplastic Fe–S cluster assembly machinery.

Methods of increasing biomass productivity, lipid induction, and controlling metabolites in algae for production of biofuels using biochemical stimulants

Abstract: The present disclosure provides methods of enhancing the biofuel potential of an algal culture, the ability of an algal culture to provide a biofuel such as a lipid or to be processed to a biofuel, the method comprising: contacting an algal culture with a composition selected to enhance the biofuel potential of an algal culture; and allowing the algal culture to incubate to the point where the potential of the algal culture to provide a biofuel product or be processed to a biofuel product is enhanced compared to when the algal culture is not in contact with the composition. The selected algal species can be a species of a genus selected from the group consisting of: Gloeocystis, Limnothrix, Scenedesmus, Chlorococcum, Chlorella, Anabaena, Chlamydomonas, Botryococcus, Cricosphaera, Spirulina, Nannochloris, Dunaliella, Phaeodactylum, Pleurochrysis, Tetraselmis, or any combination thereof, one suitable species being Chlorella sorokiniana. In some embodiments, the composition selected to enhance the biofuel potential of an algal culture can be a pesticide such as, but not limited to, malathion (2-(dimethoxyphosphinothioylthio)butanedioic acid diethyl ester).

Ascorbate and glutathione: the heart of the redox hub.

Abstract: The discovery that there is a close relationship between ascorbate and glutathione dates from soon after the characterization of the chemical formulae of the two molecules ([Szent-Gyorgyi, 1931][1]; [Hopkins and Morgan, 1936][2]). Similarly, it has long been known that thylakoids can generate

Nutrient recovery from wastewater streams by microalgae: Status and prospects

Abstract: Disposal of wastewater often results in high nutrient loading into aquatic environments, which may lead to favorable conditions for undesirable phytoplankton blooms. Microalgae are efficient in removing nitrogen, phosphorus, and toxic metals from wastewater under controlled environments. If key nutrients in the wastewater stream can be used to grow microalgae for biofuel production, the nutrients can be removed, thus significantly reducing the risk of harmful phytoplankton overgrowth. This review paper summarizes the major nutrient components of different wastewater streams, the mechanisms of algal nutrient uptake, nutrient removal performance of various species of microalgae when cultured in wastewater, and current microalgae production systems. Finally, new algae cultivation technologies applicable for biofuel production and nutrient recovery in polluted water bodies are discussed.

Glutathione in plants: an integrated overview.

Abstract: Plants cannot survive without glutathione (γ-glutamylcysteinylglycine) or γ-glutamylcysteine-containing homologues. The reasons why this small molecule is indispensable are not fully understood, but it can be inferred that glutathione has functions in plant development that cannot be performed by other thiols or antioxidants. The known functions of glutathione include roles in biosynthetic pathways, detoxification, antioxidant biochemistry and redox homeostasis. Glutathione can interact in multiple ways with proteins through thiol-disulphide exchange and related processes. Its strategic position between oxidants such as reactive oxygen species and cellular reductants makes the glutathione system perfectly configured for signalling functions. Recent years have witnessed considerable progress in understanding glutathione synthesis, degradation and transport, particularly in relation to cellular redox homeostasis and related signalling under optimal and stress conditions. Here we outline the key recent advances and discuss how alterations in glutathione status, such as those observed during stress, may participate in signal transduction cascades. The discussion highlights some of the issues surrounding the regulation of glutathione contents, the control of glutathione redox potential, and how the functions of glutathione and other thiols are integrated to fine-tune photorespiratory and respiratory metabolism and to modulate phytohormone signalling pathways through appropriate modification of sensitive protein cysteine residues.