Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: Paulinella chromatophora

Sortuj według:

Ogranicz wyniki do:

Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik

Protein translocons in photosynthetic organelles of Paulinella chromatophora

100%

Gagat P., Mackiewicz P.

Acta Societatis Botanicorum Poloniae

2014

tom 83

nr 4

The rhizarian amoeba Paulinella chromatophora harbors two photosynthetic cyanobacterial endosymbionts (chromatophores), acquired independently of primary plastids of glaucophytes, red algae and green plants. These endosymbionts have lost many essential genes, and transferred substantial number of genes to the host nuclear genome via endosymbiotic gene transfer (EGT), including those involved in photosynthesis. This indicates that, similar to primary plastids, Paulinella endosymbionts must have evolved a transport system to import their EGT-derived proteins. This system involves vesicular trafficking to the outer chromatophore membrane and presumably a simplified Tic-like complex at the inner chromatophore membrane. Since both sequenced Paulinella strains have been shown to undergo differential plastid gene losses, they do not have to possess the same set of Toc and Tic homologs. We searched the genome of Paulinella FK01 strain for potential Toc and Tic homologs, and compared the results with the data obtained for Paulinella CCAC 0185 strain, and 72 cyanobacteria, eight Archaeplastida as well as some other bacteria. Our studies revealed that chromatophore genomes from both Paulinella strains encode the same set of translocons that could potentially create a simplified but fully-functional Tic-like complex at the inner chromatophore membranes. The common maintenance of the same set of translocon proteins in two Paulinella strains suggests a similar import mechanism and/or supports the proposed model of protein import. Moreover, we have discovered a new putative Tic component, Tic62, a redox sensor protein not identified in previous comparative studies of Paulinella translocons.

Paulinella chromatophora - rethinking the transition from endosymbiont to organelle

100%

Nowack E. C. M.

Acta Societatis Botanicorum Poloniae

2014

tom 83

nr 4

Eukaryotes co-opted photosynthetic carbon fixation from prokaryotes by engulfing a cyanobacterium and stably integrating it as a photosynthetic organelle (plastid) in a process known as primary endosymbiosis. The sheer complexity of interactions between a plastid and the surrounding cell that started to evolve over 1 billion years ago, make it challenging to reconstruct intermediate steps in organelle evolution by studying extant plastids. Recently, the photosynthetic amoeba Paulinella chromatophora was identified as a much sought-after intermediate stage in the evolution of a photosynthetic organelle. This article reviews the current knowledge on this unique organism. In particular it describes how the interplay of reductive genome evolution, gene transfers, and trafficking of host-encoded proteins into the cyanobacterial endosymbiont contributed to transform the symbiont into a nascent photosynthetic organelle. Together with recent results from various other endosymbiotic associations a picture emerges that lets the targeting of host-encoded proteins into bacterial endosymbionts appear as an early step in the establishment of an endosymbiotic relationship that enables the host to gain control over the endosymbiont.

Ograniczanie wyników

2 Acta Societatis Botanicorum Poloniae

1 Gagat P.

1 Mackiewicz P.

1 Nowack E. C. M.

2 2014

Wyniki wyszukiwania

Protein translocons in photosynthetic organelles of Paulinella chromatophora

Paulinella chromatophora - rethinking the transition from endosymbiont to organelle