Functional analysis of the Brassica napus L. Phytoene Synthase (PSY) gene family
Author
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López Emparán, Ada
Author
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Quezada Martínez, Daniela
Author
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Zúñiga Bustos, Matías
Author
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Cifuentes Guzmán, Víctor
Author
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Iñiguez Luy, Federico
Author
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Federico, María Laura
Admission date
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2018-12-20T14:06:24Z
Available date
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2018-12-20T14:06:24Z
Publication date
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2014
Cita de ítem
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PLoS ONE, Volumen 9, Issue 12, 2018,
Identifier
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19326203
Identifier
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10.1371/journal.pone.0114878
Identifier
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https://repositorio.uchile.cl/handle/2250/153943
Abstract
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Phytoene synthase (PSY) has been shown to catalyze the first committed and rate-limiting step of carotenogenesis in several crop species, including Brassica napus L. Due to its pivotal role, PSY has been a prime target for breeding and metabolic engineering the carotenoid content of seeds, tubers, fruits and flowers. In Arabidopsis thaliana, PSY is encoded by a single copy gene but small PSY gene families have been described in monocot and dicotyledonous species. We have recently shown that PSY genes have been retained in a triplicated state in the A- and C-Brassica genomes, with each paralogue mapping to syntenic locations in each of the three "Arabidopsislike" subgenomes. Most importantly, we have shown that in B. napus all six members are expressed, exhibiting overlapping redundancy and signs of subfunctionalization among photosynthetic and non photosynthetic tissues. The question of whether this large PSY family actually encodes six functional enzymes remained to be answered.
Therefore, the objectives of this study were to: (i) isolate, characterize and compare the complete protein coding sequences (CDS) of the six B. napus PSY genes; (ii) model their predicted tridimensional enzyme structures; (iii) test their phytoene synthase
activity in a heterologous complementation system and (iv) evaluate their individual expression patterns during seed development. This study further confirmed that the six B. napus PSY genes encode proteins with high sequence identity, which have evolved under functional constraint. Structural modeling demonstrated that they share similar
tridimensional protein structures with a putative PSY active site. Significantly, all six B. napus PSY enzymes were found to be functional. Taking into account the specific patterns of expression exhibited by these PSY genes during seed development and
recent knowledge of PSY suborganellar localization, the selection of transgene candidates for metabolic engineering the carotenoid content of oilseeds is discussed