Biomedical subjects

E Mösinger

Publications and source records attributed to E Mösinger.

8 recordsLinked to original sources

PubMed1998

Structure, expression and localization of a germin-like protein in barley (Hordeum vulgare L.) that is insolubilized in stressed leaves.

The primary leaves of young barley seedlings contain two major, extracellular, acid-soluble proteins of ca. 22 and 23 kDa apparent molecular mass. These proteins disappeared from the intercellular washing fluid upon stress treatments that enhanced H2O2 levels and that induced resistance to subsequent challenge by the powdery mildew fungus Erysiphe graminis f. sp. hordei. A partial peptide sequence of the 22 kDa protein was determined, and a cDNA clone was isolated. The 22 kDa protein belongs the the group of germin-like proteins (GLPs) and was designated HvGLP1. Despite its similarity to germin, i.e. oxalate oxidase, no oxalate oxidase activity of HvGLP1 could be detected. The RNA and soluble protein of HvGLP1 was highly abundant in young leaves, less abundant in older leaves and absent in roots. HvGLP1 RNA oscillated with a circadian rhythm, the minimum and maximum of RNA abundance being at the end of the dark and light periods, respectively. Heat and H2O2 treatment as well as pathogen infection caused disappearance of HvGLP1 protein from the fraction of soluble proteins of the intercellular space. HvGLP1 protein could be re-solubilized from cell walls of heat- or H2O2-treated leaves by boiling in SDS suggesting non-covalent cross linking. Although a physiological role of HvGLP1 insolubilization is still open, the protein may serve as marker for oxidative stress in cereals.

Amino Acid Sequence↗

PubMed1997

NMR solution structure of the pathogenesis-related protein P14a.

The nuclear magnetic resonance (NMR) structure of the 15 kDa pathogenesis-related protein P14a, which displays antifungicidal activity and is induced in tomato leaves as a response to pathogen infection, was determined using 15N/13C doubly labeled and unlabeled protein samples. In all, 2030 conformational constraints were collected as input for the distance geometry program DIANA. After energy-minimization with the program OPAL the 20 best conformers had an average root-mean-square deviation value relative to the mean coordinates of 0.88 A for the backbone atoms N, C(alpha) and C', and 1.30 A for all heavy atoms. P14a contains four alpha-helices (I to IV) comprising residues 4 to 17, 27 to 40, 64 to 72 and 93 to 98, a short 3(10)-helix of residues 73 to 75 directly following helix III, and a mixed, four-stranded beta-sheet with topology +3x, -2x, +1, containing the residues 24-25, 53 to 58, 104 to 111 and 117 to 124. These regular secondary structure elements form a novel, complex alpha + beta topology in which the alpha-helices I, III and IV and the 3(10)-helix are located above the plane defined by the beta-sheet, and the alpha-helix II lies below this plane. The alpha-helices and beta-strands are thus arranged in three stacked layers, which are stabilized by two distinct hydrophobic cores associated with the two layer interfaces, giving rise to an "alpha-beta-alpha sandwich". The three-dimensional structure of P14a provides initial leads for identification of the so far unknown active sites and the mode of action of the protein, which is of direct interest for the generation of transgenic plants with improved host defense properties.

Amino Acid Sequence↗

PubMed1995

Pathogenesis-related PR-1 proteins are antifungal. Isolation and characterization of three 14-kilodalton proteins of tomato and of a basic PR-1 of tobacco with inhibitory activity against Phytophthora infestans.

Three distinct basic 14-kD proteins, P14a, P14b, and P14c, were isolated from tomato (Lycopersicon esculentum Mill. cv Baby) leaves infected with Phytophthora infestans. They exhibited antifungal activity against P. infestans both in vitro (inhibition of zoospore germination) and in vivo with a tomato leaf disc assay (decrease in infected leaf surface). Serological cross-reactions and amino acid sequence comparisons showed that the three proteins are members of the PR-1 group of pathogenesis-related (PR) proteins. P14a and P14b showed high similarity to a previously characterized P14, whereas P14c was found to be very similar to a putative basic-type PR-1 from tobacco predicted from isolated DNA clones. This protein, named PR-1 g, was purified from virus-infected tobacco (Nicotiana tabacum Samsun NN) leaves and characterized by amino acid microsequencing, along with the well-known acidic tobacco PR-1a, PR-1b, and PR-1c. The various tomato and tobacco PR-1 proteins were compared for their biological activity and found to display differential fungicidal activity against P. infestans in both the in vitro and in vivo assays, the most efficient being the newly characterized tomato P14c and tobacco PR-1g.

Amino Acid Sequence↗

PubMed1994

Initiator-dependent transcription in vitro by a wheat germ chromatin extract.

The development of plant in vitro transcription systems transcribing faithfully and efficiently from a broad range of plant nuclear promoters has remained a challenge. We examined the nucleotide sequence requirements for faithful and efficient transcription in a wheat germ chromatin extract (Yamazaki et al., Plant Mol Biol Rep 8: 114-123). The wheat germ chromatin extract was tested with a series of chimeric promoter constructs containing plant promoter sequences upstream from the TATA box, TATA boxes, and cap-site sequences (from -10 to +14, relative to the major in vivo initiation site) in different combinations. The plant extract transcribed faithfully from several chimeric promoters containing the capsite sequence of the parsley chalcone synthase promoter. The transcription was sensitive to the RNA polymerase II-specific inhibitor alpha-amanitin and was only dependent on the chalcone synthase cap-site sequence which therefore fulfils the operational criteria for a plant initiator element. Mutations of the putative chalcone synthase initiator element defined a core sequence '5'TAACAAC' around the initiation site that was necessary for efficient transcription in vitro. In contrast to the extract, purified wheat germ RNA polymerase II showed no preference for transcription from the major chalcone synthase in vivo initiation site.

Base Sequence↗

PubMed1988

Phytochrome regulation of greening in barley-effects on chlorophyll accumulation.

Red light treatment of dark-grown 6-day-old barley seedlings (Hordeum vulgare L.) strongly reduces the lag in chlorophyll accumulation in subsequent white light over that found in dark control seedlings placed under white light. Fluence-response studies show that the effect has both very low fluence and low fluence components. Kinetic studies indicate that the reduction in lag begins immediately following either a low fluence or a very low fluence red irradiation, with the initial rate of change significantly lower after the very low fluence treatment and showing sharp far red-absorbing form of phytochrome dependence. In both cases, the effect is maximal after roughly 4 hours, either remaining fairly constant (very low fluence) or declining somewhat (low fluence) thereafter. Saturating far red light alone yields a response equivalent to very low fluence red, and will reverse only the low fluence component of the red response. Escape from far red reversibility occurs gradually over about a 3 hour period. Since the kinetics described here differ from those in the literature related to phytochrome effects on transcription of the mRNA for the light-harvesting chlorophyll a/b-binding protein, we conclude that the phytochrome-regulated component of chlorophyll accumulation is not limited by transcription of the mRNA for its major apoprotein. Leaf segments vacuum-infiltrated with water retain the capacity to green in white light. If they are infiltrated with mannitol solutions of various concentrations, their capacity to green declines sharply at concentrations above 0.2 molar. These results bear on interpretation of run-on transcription experiments with isolated nuclei: preparation of the nuclei involves enzymic digestion of the tissue in the presence of 0.7 molar mannitol for 2.5 hours, to obtain protoplasts prior to breaking the cells. The results here make it unlikely that normal transcriptional regulation is occurring during this procedure.

Journal Article↗

PubMed1988

Phytochrome regulation of greening in barley : effects on mRNA abundance and on transcriptional activity of isolated nuclei.

Red light treatment of etiolated barley (Hordeum vulgare L.) seedlings causes an increase in the relative abundance of the mRNA for light-harvesting, chlorophyll a/b-binding polypeptides, and a decrease in the relative abundance of the mRNA for the NADPH:protochlorophyllide oxidoreductase. It also increases transcriptional activity of subsequently isolated nuclei for the mRNA for the chlorophyll-binding polypeptides and reduces it for the reductase. These results confirm those published previously. Fluence-response and kinetic studies support the hypothesis that the abundance of mRNA for the chlorophyll-binding polypeptides may be transcriptionally limited. They do not support the same hypothesis for the reductase. Red light treatments in the very low fluence range significantly decrease transcriptional activity in isolated nuclei for RNAs hybridizable by the reductase probe, but have little effect on mRNA abundance. By contrast, red light treatments in the low fluence range bring about a sharp decrease in reductase mRNA abundance with little further effect on transcription, suggesting light regulation at the level of mRNA stability rather than transcription. The fluence-response relationships for increase in abundance of mRNA for the chlorophyll-binding polypeptides is similar to that published elsewhere for elimination of the lag period of chlorophyll accumulation in barley. However, kinetic studies published elsewhere show that for elimination of the lag in chlorophyll accumulation, the dependence on the far red-absorbing form of phytochrome concentration is significantly different from the dependence of the transcriptional changes, suggesting that although transcription might be what limits mRNA abundance for the chlorophyll-binding proteins, the mRNA abundance can not be what limits chlorophyll accumulation per se.

Journal Article↗

PubMed1986

The implication of a plastid-derived factor in the transcriptional control of nuclear genes encoding the light-harvesting chlorophyll a/b protein.

In carotenoid-deficient albina mutants of barley and in barley plants treated with the herbicide Norflurazon the light-dependent accumulation of the mRNA for the light-harvesting chlorophyll a/b protein (LHCP) is blocked. Thus, the elimination of a functional chloroplast, either as a result of mutation or as a result of herbicide treatment, can lead to the specific suppression of the expression of a nuclear gene encoding a plastid-localized protein. These results confirm and extend earlier observations on maize [Mayfield and Taylor (1984) Eur. J. Biochem. 144, 79-84]. The inhibition of mRNA accumulation appears to be specific for the LHCP; the mRNAs encoding the small subunit of ribulose-1,5-bisphosphate carboxylase and the NADPH: protochlorophyllide oxidoreductase are relatively unaffected. The failure of the albina mutants and of Norflurazon-treated plants to accumulate the LHCP mRNA is not exclusively caused by an instability of the transcript but rather by the inability of the plants to enhance the rate of transcription of the LHCP genes during illumination. Several chlorophyll-deficient xantha mutants of barley, which are blocked after protoporphyrin IX or Mg-protoporphyrin, and the chlorophyll-b-less mutant chlorina f2 accumulate the LHCP mRNA to almost normal levels during illumination. Thus, if any of the reactions leading to chlorophyll formation is involved in the control of LHCP mRNA accumulation it should be one between the formation of protochlorophyllide and the esterification of chlorophyllide a. While the nature of the regulatory factor(s) has not been identified our results suggest that, in addition to phytochrome (Pfr), plastid-dependent factors are required for a continuous light-dependent transcription of nuclear genes encoding the LHCP.

Carotenoids↗

PubMed1985

Phytochrome control of in vitro transcription of specific genes in isolated nuclei from barley (Hordeum vulgare).

The transcriptional rates of four different genes in shoots of barley grown under different light regimes were quantified by monitoring nuclear RNA transcripts using gene-specific hybridization probes. Isolated nuclei were pulse-labelled with [alpha-32P]UTP and the relative rates of light-harvesting chlorophyll a/b protein (LHCP) mRNA, NADPH:protochlorophyllide oxidoreductase mRNA, B1 hordein mRNA, and 26-S rRNA synthesis were measured. Irradiation of dark-grown plants with a red light pulse increased the rate of LHCP mRNA synthesis tenfold within 3 h, and the rate of rRNA synthesis more than twofold within 9 h. The relative rate of synthesis of the oxidoreductase mRNA decreased following a red light pulse reaching a minimum after 3-6 h. As a direct proof of phytochrome involvement in the light-induced stimulation of LHCP and the repression of the oxidoreductase transcripts for both responses, red/far-red reversibility could be demonstrated. We conclude that phytochrome is able both to increase the transcription of certain nuclear genes and decrease the transcription of others.

Cell Nucleus↗