title: Arabidopsis Squalene Epoxidase 3 (SQE3) Complements SQE1 and Is Important for Embryo Development and Bulk Squalene Epoxidase Activity.
abstract: The existence of multigenic families in the mevalonate pathway suggests divergent functional roles for pathway components involved in the biosynthesis of plant sterols. Squalene epoxidases (SQEs) are key components of this pathway, and Squalene Epoxidase 1 (SQE1) has been identified as a fundamental enzyme in this biosynthetic step. In the present work, we extended the characterization of the remaining SQE family members, phylogenetically resolving between true SQEs and a subfamily of SQE-like proteins that is exclusive to Brassicaceae. Functional characterization of true SQE family members, Squalene Epoxidase 2 (SQE2) and Squalene Epoxidase 3 (SQE3), indicates that SQE3, but not SQE2, contributes to the bulk SQE activity in Arabidopsis, with sqe3-1 mutants accumulating squalene and displaying sensitivity to terbinafine. We genetically demonstrated that SQE3 seems to play a particularly significant role in embryo development. Also, SQE1 and SQE3 both localize in the endoplasmic reticulum, and SQE3 can functionally complement SQE1. Thus, SQE1 and SQE3 seem to be two functionally unequal redundant genes in the promotion of plant SQE activity in Arabidopsis.
authors.affiliation: Center for Biodiversity, Functional & Integrative Genomics (BioFIG), Plant Functional Biology Center, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
authors.forename: Sara
authors.initials: S
authors.lastname: Laranjeira
authors.affiliation: Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora", Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Departmento de Biología Molecular y Bioquímica, Universidad de Málaga, Campus Teatinos, 29071 Málaga, Spain.
authors.forename: Vitor
authors.initials: V
authors.lastname: Amorim-Silva
authors.affiliation: Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora", Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Departmento de Biología Molecular y Bioquímica, Universidad de Málaga, Campus Teatinos, 29071 Málaga, Spain.
authors.forename: Alicia
authors.initials: A
authors.lastname: Esteban
authors.affiliation: Department of Molecular Genetics, Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra-Cerdanyola del Vallés, 08193, Spain; Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, University of Barcelona, 08028 Barcelona, Spain.
authors.forename: Monserrat
authors.initials: M
authors.lastname: Arró
authors.affiliation: Department of Molecular Genetics, Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra-Cerdanyola del Vallés, 08193, Spain; Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, University of Barcelona, 08028 Barcelona, Spain.
authors.forename: Albert
authors.initials: A
authors.lastname: Ferrer
authors.affiliation: Center for Biodiversity, Functional & Integrative Genomics (BioFIG), Plant Functional Biology Center, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
authors.forename: Rui Manuel
authors.initials: RM
authors.lastname: Tavares
authors.affiliation: Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora", Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Departmento de Biología Molecular y Bioquímica, Universidad de Málaga, Campus Teatinos, 29071 Málaga, Spain.
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Botella
authors.affiliation: Canada Research Chair in Plant Physiology and Cellular Dynamics, Department of Botany, Faculty of Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada. Electronic address: abel.rosado@botany.ubc.ca.
authors.forename: Abel
authors.initials: A
authors.lastname: Rosado
authors.affiliation: CIBIO, InBIO - Research Network in Biodiversity and Evolutionary Biology, Universidade do Porto, Campus Agrário de Vairão, 4485-661 Vairão, Portugal. Electronic address: hazevedo@cibio.up.pt.
authors.forename: Herlânder
authors.initials: H
authors.lastname: Azevedo
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D009154:Mutation; D010802:Phylogeny; D021381:Protein Transport; D012639:Seeds / Q000166:cytology / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D050603:Squalene Monooxygenase / Q000235:genetics* / Q000378:metabolism*
chemical_list: D050603:Squalene Monooxygenase
keywords: Arabidopsis; MVA pathway; embryo development; squalene epoxidase; sterol biosynthesis