Evolutionary conservation of dual Sec translocases in the cyanelles of Cyanophora paradoxaReportar como inadecuado

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BMC Evolutionary Biology

, 8:304

First Online: 01 November 2008Received: 11 March 2008Accepted: 01 November 2008


BackgroundCyanelles, the peptidoglycan-armored plastids of glaucocystophytes, occupy a unique bridge position in between free-living cyanobacteria and chloroplasts. In some respects they side with cyanobacteria whereas other features are clearly shared with chloroplasts. The Sec translocase, an example for -conservative sorting- in the course of evolution, is found in the plasma membrane of all prokaryotes, in the thylakoid membrane of chloroplasts and in both these membrane types of cyanobacteria.

ResultsIn this paper we present evidence for a dual location of the Sec translocon in the thylakoid as well as inner envelope membranes of the cyanelles from Cyanophora paradoxa, i. e. conservative sorting sensu stricto. The prerequisite was the generation of specific antisera directed against cyanelle SecY that allowed immunodetection of the protein on SDS gels from both membrane types separated by sucrose density gradient floatation centrifugation. Immunoblotting of blue-native gels yielded positive but differential results for both the thylakoid and envelope Sec complexes, respectively. In addition, heterologous antisera directed against components of the Toc-Tic translocons and binding of a labeled precursor protein were used to discriminate between inner and outer envelope membranes.

ConclusionThe envelope translocase can be envisaged as a prokaryotic feature missing in higher plant chloroplasts but retained in cyanelles, likely for protein transport to the periplasm. Candidate passengers are cytochrome c6 and enzymes of peptidoglycan metabolism. The minimal set of subunits of the Toc-Tic translocase of a primitive plastid is proposed.

Electronic supplementary materialThe online version of this article doi:10.1186-1471-2148-8-304 contains supplementary material, which is available to authorized users.

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Autor: Fumie Yusa - Jürgen M Steiner - Wolfgang Löffelhardt

Fuente: https://link.springer.com/article/10.1186/1471-2148-8-304

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