Response to the Sexual Pheromone and Wounding in the Green Alga Volvox: Induction of an Extracellular Glycoprotein Consisting Almost Exclusively of Hydroxyproline

Ender, Frank; Hallmann, Armin; Amon, Peter; Sumper, Manfred

doi:10.1074/jbc.274.49.35023

Cited by 29 publications

(23 citation statements)

References 47 publications

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“…Whereas many chimeric HRGPs in algae and higher plants resemble the agglutinins and Gp1 in having a single long P-rich sequence interconnecting, and perhaps penetrating, globular N-terminal and/or C-terminal domains (Baldwin et al, 1992;Ertl et al, 1992;Rubinstein et al, 1995;Woessner and Goodenough, 1989;Waffenschmidt et al, 1993;Wu et al, 1993;Woessner et al, 1994;Godl et al, 1997;Schultz et al, 1997;Ender et al, 1999Ender et al, , 2002Rodriguez et al, 1999;Bosch et al, 2001;Hallmann et al, 2001), other chimeric HRGPs have short P-rich segments that would at best form very short shafts (L. Song and W.L. Dentler, unpublished data, GenBank AF508983; Sumper and Hallmann, 1998;R.A.…”

Section: Organization Of Chimeric Hrgpsmentioning

confidence: 99%

PlusandMinusSexual Agglutinins fromChlamydomonas reinhardtii

et al. 2005

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Gametes of the unicellular green alga Chlamydomonas reinhardtii undergo sexual adhesion via enormous chimeric Hyp-rich glycoproteins (HRGPs), the plus and minus sexual agglutinins, that are displayed on their flagellar membrane surfaces. We have previously purified the agglutinins and analyzed their structural organization using electron microscopy. We report here the cloning and sequencing of the Sag1 and Sad1 genes that encode the two agglutinins and relate their derived amino acid sequences and predicted secondary structure to the morphology of the purified proteins. Both agglutinin proteins are organized into three distinct domains: a head, a shaft in a polyproline II configuration, and an N-terminal domain. The plus and minus heads are related in overall organization but poorly conserved in sequence except for two regions of predicted hydrophobic a-helix. The shafts contain numerous repeats of the PPSPX motif previously identified in Gp1, a cell wall HRGP. We propose that the head domains engage in autolectin associations with the distal termini of their own shafts and suggest ways that adhesion may involve head-head interactions, exolectin interactions between the heads and shafts of opposite type, and antiparallel shaft-shaft interactions mediated by carbohydrates displayed in polyproline II configurations.

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Section: Organization Of Chimeric Hrgpsmentioning

confidence: 99%

PlusandMinusSexual Agglutinins fromChlamydomonas reinhardtii

et al. 2005

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“…It is known that the expression of several Volvox genes is promoted not only by the sex inducer but also by mechanical wounding (Amon et al, 1998;Ender et al, 1999;Hallmann et al, 2001;Hallmann, 2006Hallmann, , 2007. To investigate the influence of mechanical wounding on the expression of VChR, Volvox females were wounded and incubated for 1 h under standard conditions.…”

Section: The Influence Of Light and Stress Conditions On The Expressimentioning

confidence: 99%

Channelrhodopsins ofVolvox carteriAre Photochromic Proteins That Are Specifically Expressed in Somatic Cells under Control of Light, Temperature, and the Sex Inducer

et al. 2009

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Channelrhodopsins are light-gated ion channels involved in the photoresponses of microalgae. Here, we describe the characterization of two channelrhodopsins, Volvox channelrhodopsin-1 (VChR1) and VChR2, from the multicellular green alga Volvox carteri. Both are encoded by nuclear single copy genes and are highly expressed in the small biflagellated somatic cells but not in the asexual reproductive cells (gonidia). Expression of both VChRs increases after cell cleavage and peaks after completion of embryogenesis, when the biosynthesis of the extracellular matrix begins. Likewise, expression of both transcripts increases after addition of the sex-inducer protein, but VChR2 is induced much more than VChR1. The expression of VChR1 is specifically promoted by extended dark periods, and heat stress reduces predominantly VChR1 expression. Expression of both VChRs increased under low light conditions, whereas cold stress and wounding reduced expression. Both VChRs were spectroscopically studied in their purified recombinant forms. VChR2 is similar to the ChR2 counterpart from Chlamydomonas reinhardtii with respect to its absorption maximum (460 nm) and photocycle dynamics. In contrast, VChR1 absorbs maximally at 540 nm at low pH (D540), shifting to 500 nm at high pH (D500). Flash photolysis experiments showed that after light excitation, the D540 dark state bleaches and at least two photoproducts, P600 and P500, are sequentially populated during the photocycle. We hypothesize that VChR2 is a general photoreceptor that is responsible for the avoidance of blue light and might play a key role in sexual development, whereas VChR1 is the main phototaxis photoreceptor under vegetative conditions, as it is more specifically adapted to environmental conditions and the developmental stages of Volvox.

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“…Previously, HRGP gene expression has been shown to be induced in response to wounding (Ahn et al, 1996). This may be an ancient wound response, as it is also observed in alga (Ender et al, 1999).…”

Section: Transcript Abundance Both Increased and Decreased In Responsmentioning

confidence: 99%

The response of the poplar transcriptome to wounding and subsequent infection by a viral pathogen

et al. 2004

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Summary• The Populus-Poplar Mosaic Virus (PopMV) pathosystem is the best characterized of all forest tree-virus interactions. The details of the host response to this virus are completely unknown.• The transcript abundance for approximately 10 000 Populus genes was simultaneously interrogated using spotted cDNA microarrays. Relative transcript abundance was compared for RNA extracted from Populus leaves that were untreated, mockinoculated leaves that were wounded by leaf abrasion and inoculated leaves that were abraded and then infected by virus.• Statistical analysis of the microarray data identified suites of genes that exhibited increased or decreased transcript abundance in response to wounding, systemic PopMV infection or both together. Genes implicated in programmed cell death, and cell wall reinforcement were a major feature of the wound response, whereas genes encoding metallothionein-like proteins, and proteins implicated in cell wall remodelling were a major feature of the PopMV response.• The identification of wound-and PopMV-regulated genes opens the door for future studies aimed at testing specific hypotheses related to the mechanisms used by forest trees to contend with stress.

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Response to the Sexual Pheromone and Wounding in the Green Alga Volvox: Induction of an Extracellular Glycoprotein Consisting Almost Exclusively of Hydroxyproline

Cited by 29 publications

References 47 publications

PlusandMinusSexual Agglutinins fromChlamydomonas reinhardtii

PlusandMinusSexual Agglutinins fromChlamydomonas reinhardtii

Channelrhodopsins ofVolvox carteriAre Photochromic Proteins That Are Specifically Expressed in Somatic Cells under Control of Light, Temperature, and the Sex Inducer

The response of the poplar transcriptome to wounding and subsequent infection by a viral pathogen

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