Diversity and evolution of phycobilisomes in marine Synechococcusspp.: a comparative genomics studyReportar como inadecuado




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Genome Biology

, 8:R259

First Online: 05 December 2007Received: 23 July 2007Revised: 22 October 2007Accepted: 05 December 2007

Abstract

BackgroundMarine Synechococcus owe their specific vivid color ranging from blue-green to orange to their large extrinsic antenna complexes called phycobilisomes, comprising a central allophycocyanin core and rods of variable phycobiliprotein composition. Three major pigment types can be defined depending on the major phycobiliprotein found in the rods phycocyanin, phycoerythrin I or phycoerythrin II. Among strains containing both phycoerythrins I and II, four subtypes can be distinguished based on the ratio of the two chromophores bound to these phycobiliproteins. Genomes of eleven marine Synechococcus strains recently became available with one to four strains per pigment type or subtype, allowing an unprecedented comparative genomics study of genes involved in phycobilisome metabolism.

ResultsBy carefully comparing the Synechococcus genomes, we have retrieved candidate genes potentially required for the synthesis of phycobiliproteins in each pigment type. This includes linker polypeptides, phycobilin lyases and a number of novel genes of uncharacterized function. Interestingly, strains belonging to a given pigment type have similar phycobilisome gene complements and organization, independent of the core genome phylogeny as assessed using concatenated ribosomal proteins. While phylogenetic trees based on concatenated allophycocyanin protein sequences are congruent with the latter, those based on phycocyanin and phycoerythrin notably differ and match the Synechococcus pigment types.

ConclusionWe conclude that the phycobilisome core has likely evolved together with the core genome, while rods must have evolved independently, possibly by lateral transfer of phycobilisome rod genes or gene clusters between Synechococcus strains, either via viruses or by natural transformation, allowing rapid adaptation to a variety of light niches.

AbbreviationsAPallophycocyanin

LCcore linker

LCMcore-membrane linker

LiDSlithium dodecyl sulphate

LRrod linker

LRCrod-core linker

MLmaximum likelihood

MPmaximum parsimony

NJneighbor joining

ORFopen reading frame

PBSphycobilisome

PCphycocyanin

PCBphycocyanobilin

PEphycoerythrin

PEBphycoerythrobilin

PUBphycourobilin.

Electronic supplementary materialThe online version of this article doi:10.1186-gb-2007-8-12-r259 contains supplementary material, which is available to authorized users.

Christophe Six, Jean-Claude Thomas and Frédéric Partensky contributed equally to this work.

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Autor: Christophe Six - Jean-Claude Thomas - Laurence Garczarek - Martin Ostrowski - Alexis Dufresne - Nicolas Blot - David J Sca

Fuente: https://link.springer.com/







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