Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 511209
Title Cloning, molecular characterization, and phylogeny of two evolutionary distinct glutamine synthetase isoforms in the green microalga Haematococcus pluvialis (Chlorophyceae)
Author(s) Reinecke, Diana L.; Zarka, Aliza; Leu, Stefan; Boussiba, Sammy
Source Journal of Phycology 52 (2016)6. - ISSN 0022-3646 - p. 961 - 972.
Department(s) FBR Bioconversion
Publication type Refereed Article in a scientific journal
Publication year 2016
Keyword(s) alga biotechnology - Archaeplastida - Astaxanthin - Charophyta - glutamine synthetase - green plant evolution - horizontal gene transfer - Lycopodiophyta - nitrogen uptake - transcript regulation

Haematococcus pluvialis (Chlorophyta) is a widely used microalga of great economic potential, yet its molecular genetics and evolution are largely unknown. We present new detailed molecular and phylogenetic analysis of two glutamine synthetase (GS) enzymes and genes (gln) under the Astaxanthin-inducing conditions of light- and nitrogen-stress. Structure analysis identified key residues and confirmed two decameric GS2 holoenzymes, a cytoplasmic enzyme, termed GS2c, and a plastidic form, termed GS2p, due to chloroplast-transit peptides at its N-terminus. Gene expression analysis showed dissociation of mRNA, protein, and enzyme activity levels for both GS2 under different growth conditions, indicating the strong post-transcriptional regulation. Data-mining identified novel and specified published gln genes from Prasinophyceae, Chlorophyta, Trebouxiophyceae, Charophyceae, Bryophyta, Lycopodiophyta, Spermatophyta, and Rhodophyta. Phylogenetic analysis found homologues to the cytosolic GS2c of H. pluvialis in all other photo- and non-photosynthetic Eukaryota. The chloroplastic GS2p was restricted to Chlorophyta, Bryophyta, some Proteobacteria and Fungii; no homologues were identified in Spermatophyta or other Eukaryota. This indicates two independent prokaryotic donors for these two gln genes in H. pluvialis. Combined phylogenetic analysis of GS, chl-b synthase, elongation factor, and light harvesting complex homologues project a newly refined model of Viridiplantae evolution. Herein, a GS1 evolved into the cytosolic GS2c and was passed on to all Eukaryota. Later, the chloroplastic GS2p entered the Archaeplastida lineage via a horizontal gene transfer at the divergence of Chlorophyta and Rhodophyta lineages. GS2p persisted in Chlorophyta and Bryophyta, but was lost during Spermatophyta evolution. These data suggest the revision of GS classification and nomenclature, and extend our understanding of the photosynthetic Eukaryota evolution.

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