A Small Chloroplast-Encoded Protein as a Novel Architectural Component of the Light-Harvesting Antenna

A small conserved open reading frame in the plastid genome, ycf9, encodes a putative membrane protein of 62 amino acids. To determine the function of this reading frame we have constructed a knockout allele for targeted disruption of ycf9. This allele was introduced into the tobacco plastid genome by biolistic transformation to replace the wild-type ycf9 allele. Homoplasmic ycf9 knockout plants displayed no phenotype under normal growth conditions. However, under low light conditions, their growth rate was significantly reduced as compared with the wild-type, due to a lowered efficiency of the light reaction of photosynthesis. We show that this phenotype is caused by the deficiency in a pigment–protein complex of the light-harvesting antenna of photosystem II and hence by a reduced efficiency of photon capture when light availability is limiting. Our results indicate that, in contrast to the current view, light-harvesting complexes do not only consist of the classical pigment-binding proteins, but may contain small structural subunits in addition. These subunits appear to be crucial architectural factors for the assembly and/or maintenance of stable light-harvesting complexes

Aktionsplan Flächensparen – nicht ohne Kontingentierung

Auch wenn die Neuinanspruchnahme von Flächen in den vergangenen Jahren erkennbar zurückgegangen ist und die Flächenpolitik erste Erfolge zeigt, macht die aktuelle Entwicklung deutlich, dass die vom Bund verabschiedeten flächenpolitischen Ziele nur mit einer Intensivierung der Aktivitäten und einer Schärfung des Instrumentariums erreicht werden können. Zur wirksamen Umsteuerung müssen die verbindliche Begrenzung der Neuinanspruchnahme von Flächen, die Mobilisierung von Innenentwicklungspotenzialen und die Steigerung der Flächeneffizienz verknüpft werden. Dazu müssen Bund und Länder in drei Aktionsfeldern aktiv werden: Kontingentierungssystem einführen, Innenentwicklung stärken und Raumordnung stärken

Faithful transcription initiation from a mitochondrial promoter in transgenic plastids

The transcriptional machineries of plastids and mitochondria in higher plants exhibit striking similarities. All mitochondrial genes and part of the plastid genes are transcribed by related phage-type RNA polymerases. Furthermore, the majority of mitochondrial promoters and a subset of plastid promoters show a similar structural organization. We show here that the plant mitochondrial atpA promoter is recognized by plastid RNA polymerases in vitro and in vivo. The Arabidopsis phage-type RNA polymerase RpoTp, an enzyme localized exclusively to plastids, was found to recognize the mitochondrial atpA promoter in in vitro assays suggesting the possibility that mitochondrial promoters might function as well in plastids. We have, therefore, generated transplastomic tobacco plants harboring in their chloroplast genome the atpA promoter fused to the coding region of the bacterial nptII gene. The chimeric nptII gene was found to be efficiently transcribed in chloroplasts. Mapping of the 5′ ends of the nptII transcripts revealed accurate recognition of the atpA promoter by the chloroplast transcription machinery. We show further that the 5′ untranslated region (UTR) of the mitochondrial atpA transcript is capable of mediating translation in chloroplasts. The functional and evolutionary implications of these findings as well as possible applications in chloroplast genome engineering are discussed

Der Umgang mit der sozialen Differenz Körper am Beispiel einer Beratungsstelle für Mädchen mit Essstörungen

In der Forschungsarbeit von Saskia Bock, Susanne Benzel und Stephanie Warlies wurde der Frage nachgegangen, wie in einer Beratungsstelle für Mädchen mit Essstörungen mit sozialen Differenzen umgegangen wird. Dabei wurde der Fokus auf den Körper als sozialer Differenz gelegt. Im Sinne des Intersektionalitätsansatzes wurden außerdem weitere soziale Differenzlinien miteinbezogen und deren Wechselwirkungen näher untersucht. Der Fragestellung wurde anhand eines Experteninterviews in Kombination mit einer Dokumentenanalyse nachgegangen

Y3IP1, A nucleus-encoded Thylakoid Protein, Cooperates with the Plastid-Encoded YCf3 Protein in Photosystem I Assembly of Tobacco and Arabidopsis

The intricate assembly of photosystem I (PSI), a large multiprotein complex in the thylakoid membrane, depends on auxiliary protein factors. One of the essential assembly factors for PSI is encoded by ycf3 (hypothetical chloroplast reading frame number 3) in the chloroplast genome of algae and higher plants. To identify novel factors involved in PSI assembly, we constructed an epitope-tagged version of ycf3 from tobacco (Nicotiana tabacum) and introduced it into the tobacco chloroplast genome by genetic transformation. Immunoaffinity purification of Ycf3 complexes from the transplastomic plants identified a novel nucleus-encoded thylakoid protein, Y3IP1 (for Ycf3-interacting protein 1), that specifically interacts with the Ycf3 protein. Subsequent reverse genetics analysis of Y3IP1 function in tobacco and Arabidopsis thaliana revealed that knockdown of Y3IP1 leads to a specific deficiency in PSI but does not result in loss of Ycf3. Our data indicate that Y3IP1 represents a novel factor for PSI biogenesis that cooperates with the plastid genome-encoded Ycf3 in the assembly of stable PSI units in the thylakoid membrane

Dual targeting of a mature plastoglobulin/fibrillin fusion protein to chloroplast plastoglobules and thylakoids in transplastomic tobacco plants

Plastoglobules (PG) are lipid droplets in chloroplasts and other plastid types having important functions in lipid metabolism. Plastoglobulins (PGL) also known as fibrillins (FBN) are evolutionary conserved proteins present at the PG surface but also to various extents at the thylakoid membrane. PGLs are thought to have structural functions in PG formation and maintenance. The targeting of an Arabidopsis PGL (PGL34) to PG required the full protein sequence with the exception of a short C- terminal stretch. This indicated that PGL targeting relies on correct folding rather than a discrete sequence. PGLs lack strongly hydrophic regions and may therefore extrinsically associate with PG and thylakoid membranes via interaction with hydrophilic headgroups of surface lipids. Here, we report on the expression of the Arabidopsis plastoglobulin of 35kD (PGL35 or FBN1a) expressed as a mature protein fused to HIVp24 (human immunodeficiency virus capsid particle p24) or HCV (hepatitis C virus core protein) in transplastomic tobacco. A PGL35–HIVp24 fusion targeted in part to plastoglobules but a larger proportion was recovered in the thylakoid fraction. The findings indicate that transplastomic PGL35–HIVp24 folded correctly after its synthesis inside the chloroplast and then dually targeted to plastoglobules as well as thylakoid membranes

Gender Mainstreaming: ein neues Tätigkeitsfeld für Sozialwissenschaftler/innen?

Die Verfasserinnen geben einen Einblick in den Stand der Umsetzung von Gender Mainstreaming vor allem auf Bundes- und Kommunalebene. Es wird gezeigt, was Gender Mainstreaming ist, worin sich dieses Konzept von älteren Ansätzen der Frauenförderungs- und Gleichstellungspolitik unterscheidet und welche veränderten Anforderungen es an staatliches Handeln und Verwaltungshandeln stellt. Ob die Nachfrage nach Gender-Experten, die sich im Zuge der Implementation von Gender Mainstreaming entwickelt, ein neues berufliches Tätigkeitsfeld für SozialwissenschaftlerInnen erschließt, bleibt beim gegenwärtigen Stand der Umsetzung noch offen. Für die Entwicklung eines intermediären Beratungsmarktes ist der kontinuierliche Dialog zwischen Wissenschaft und Praxis eine wichtige Voraussetzung. (ICE2