97,449 research outputs found
Myosin-cross-reactive antigen (MCRA) protein from Bifidobacterium breve is a FAD-dependent fatty acid hydratase which has a function in stress protection
Full text linkpeer-reviewedBackground The aim of this study was to determine the catalytic activity and physiological role of myosin-cross-reactive antigen (MCRA) from Bifidobacterium breve NCIMB 702258. MCRA from B. breve NCIMB 702258 was cloned, sequenced and expressed in heterologous hosts (Lactococcus and Corynebacterium) and the recombinant proteins assessed for enzymatic activity against fatty acid substrates. Results MCRA catalysed the conversion of palmitoleic, oleic and linoleic acids to the corresponding 10-hydroxy fatty acids, but shorter chain fatty acids were not used as substrates, while the presence of trans-double bonds and double bonds beyond the position C12 abolished hydratase activity. The hydroxy fatty acids produced were not metabolised further. We also found that heterologous Lactococcus and Corynebacterium expressing MCRA accumulated increasing amounts of 10-HOA and 10-HOE in the culture medium. Furthermore, the heterologous cultures exhibited less sensitivity to heat and solvent stresses compared to corresponding controls. Conclusions MCRA protein in B. breve can be classified as a FAD-containing double bond hydratase, within the carbon-oxygen lyase family, which may be catalysing the first step in conjugated linoleic acid (CLA) production, and this protein has an additional function in bacterial stress protection
Joshua Davis: Author of Spare Parts
Full text linkCitation: K-State First (2016). Joshua Davis: Author of Spare Parts [Flier]. Manhattan, Kansas: K-State First.Flyer advertising Joshua Davis's author talk at Kansas State University
Wound‐induced triacylglycerol biosynthesis is jasmonoy‐l‐isoleucin and abscisic acid independent
No full textTriacylglycerol (TAG) plays a significant role during plant stress – it maintains lipid homeostasis. Upon wounding plants accumulate TAG, likely as a storage form of fatty acids (FAs) that originate from damaged membranes. This study asked if this process depends on the two phytohormones jasmonoyl-isoleucine (JA-Ile) and abscisic acid (ABA), which are involved in wound signalling.
To analyse regulation of wound-induced TAG accumulation, we used mutants deficient in JA-Ile, with reduced ABA and the myb96 mutant, which is deficient in an ABA-dependent transcription factor. The expression of genes involved in TAG biosynthesis, and TAG content after wounding were analysed via LC–MS and GC-FID, plastidial lipid content in all mentioned mutant lines was also determined. The localization of newly synthesized TAG was investigated using lipid droplet staining.
TAG accumulation upon wounding was confirmed as well as the fact that the newly synthesized TAG are mostly composed of polyunsaturated fatty acids. Nevertheless, all tested mutant lines were able to accumulate TAG similar to the WT. We observed differences in reduction of plastidial lipids – in WT plants this was higher than in mutant lines. Newly synthesized TAGs were stored in lipid droplets at and around the wounded area.
Our results show that TAG accumulation upon wounding is not dependent on JA-Ile or ABA. The newly synthesized TAG species are composed of unsaturated fatty acids of membrane origin, and most likely serves as a transient energy store.Göttingen Graduate School of Neuroscience and Molecular Biology (GGNB)Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659Natural Sciences and Engineering Research Council of Canada http://dx.doi.org/10.13039/50110000003
Steven Johnson Author Talk Poster
No full textK-State Book NetworkA poster advertising an author talk by Steven Johnson at Kansas State University on September 3, 2014. Steven Johnson's book "The Ghost Map" was the 2014-2015 common book
Author response
Full text linkThe biotrophic fungus Ustilago maydis causes smut disease in maize with characteristic tumor formation and anthocyanin induction. Here, we show that anthocyanin biosynthesis is induced by the virulence promoting secreted effector protein Tin2. Tin2 protein functions inside plant cells where it interacts with maize protein kinase ZmTTK1. Tin2 masks a ubiquitin-proteasome degradation motif in ZmTTK1, thus stabilizing the active kinase. Active ZmTTK1 controls activation of genes in the anthocyanin biosynthesis pathway. Without Tin2, enhanced lignin biosynthesis is observed in infected tissue and vascular bundles show strong lignification. This is presumably limiting access of fungal hyphae to nutrients needed for massive proliferation. Consistent with this assertion, we observe that maize brown midrib mutants affected in lignin biosynthesis are hypersensitive to U. maydis infection. We speculate that Tin2 rewires metabolites into the anthocyanin pathway to lower their availability for other defense responses
Arabidopsis GH3 .10 conjugates jasmonates
No full textAbstract Jasmonates regulate plant development and defence. In angiosperms, the canonical bioactive jasmonate is jasmonoyl‐isoleucine (JA‐Ile), which is formed in Arabidopsis thaliana by JAR1 and GH3.10. In contrast to other jasmonate biosynthesis or perception mutants, however, gh3.10 jar1 knockout lines are still fertile. Therefore we investigated whether further jasmonates and GH3 enzymes contribute to regulation of fertility. Jasmonate levels were analysed by liquid chromatography–mass spectrometry. The substrate range of recombinant GH3.10 and related GH3 enzymes was studied using non‐targeted ex vivo metabolomics with flower and leaf extracts of A. thaliana and in vitro enzyme assays. Jasmonate application experiments were performed to study their potential bioactivity. In flowers and wounded leaves of gh3.10 jar1 knockout lines JA‐Ile was below the detection limit. While 12‐hydroxy‐JA was identified as the preferred substrate of GH3.10, no other recombinant GH3 enzymes tested were capable of JA‐Ile formation. Additional JA conjugates found in wounded leaves (JA‐Gln) or formed in flowers upon MeJA treatment in the absence of JA‐Ile (JA‐Gln, JA‐Asn, JA‐Glu) were identified. The aos gh3.10 jar1 was introduced as a novel tool to test for the bioactivity of JA‐Gln to regulate fertility. This study found JAR1 and GH3.10 are the only contributors to JA‐Ile biosynthesis in Arabidopsis and identified a number of JA conjugates as potential bioactive jasmonates acting in the absence of JA‐Ile. However, their contribution in regulating fertility is yet to be conclusively determined.Deutsche Forschungsgemeinschaft https://doi.org/10.13039/50110000165
Production of wax esters in plant seed oils by oleosomal cotargeting of biosynthetic enzymes
No full textWax esters are neutral lipids exhibiting desirable properties for lubrication. Natural sources have traditionally been whales. Additionally some plants produce wax esters in their seed oil. Currently there is no biological source available for long chain length monounsaturated wax esters that are most suited for industrial applications. This study aimed to identify enzymatic requirements enabling their production in oilseed plants. Wax esters are generated by the action of fatty acyl-CoA reductase (FAR), generating fatty alcohols and wax synthases (WS) that esterify fatty alcohols and acyl-CoAs to wax esters. Based on their substrate preference, a FAR and a WS from Mus musculus were selected for this study (MmFAR1 and Mm WS). Mm WS resides in the endoplasmic reticulum (ER), whereas MmFAR1 associates with peroxisomes. The elimination of a targeting signal and the fusion to an oil body protein yielded variants of MmFAR1 and Mm WS that were cotargeted and enabled wax ester production when coexpressed in yeast or Arabidopsis. In the fae1 fad2 double mutant, rich in oleate, the cotargeted variants of MmFAR1 and Mm WS enabled formation of wax esters containing >65% oleyl-oleate. The data suggest that cotargeting of unusual biosynthetic enzymes can result in functional interplay of heterologous partners in transgenic plants.-Heilmann, M., T. Iven, K. Ahmann, E. Hornung, S. Stymne, and I. Feussner. Production of wax esters in plant seed oils by oleosomal cotargeting of biosynthetic enzymes. J. Lipid Res. 2012. 53: 2153-2161
On the origin of fatty acid biosynthesis in Archaeplastida
No full textThis article comments on: Sato N, Ikemura E, Uemura M, Awai K. 2025. Genomic and biochemical analyses of lipid biosynthesis in Cyanophora paradoxa: limited role of the chloroplast in fatty acid synthesis. Journal of Experimental Botany 76, 532–545. https://doi.org/10.1093/jxb/erae42
Verticillium longisporum infection affects the leaf apoplastic proteome, metabolome, and cell wall properties in Arabidopsis thaliana
No full textKinetics of barley FA hydroperoxide lyase are modulated by salts and detergents
No full textThe cDNA from barley coding FA hydroperoxide lyase (HPL) was cloned. A recombinant protein derived from the cDNA was expressed in Escherichia coli as an active enzyme. Thus far, there have been no reports on HPL in monocotyledonous plants. The recombinant protein was shown to be most active to linolenic acid 13-hydroperoxide, followed by linoleic acid 13-hydroperoxide. 9-Hydroperoxides of the FA could not be substrates for the recombinant HPL. The activity was dramatically enhanced in the presence of a detergent and/or a salt in the reaction mixture. At the same time, the kinetics of the reaction, including inactivation and the V-max value of the HPL, were also greatly modulated, depending on the concentration of a monovalent cation and/or a detergent in the reaction mixture. These results suggest that these effectors induced a conformational change in barley HPL, resulting in an improvement in substrate binding and in enzyme activity
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