Dissecting the contributions of GC content and codon usage to gene expression in the model alga Chlamydomonas reinhardtii. (16th October 2015)

• Record Type: Journal Article
• Authors: Barahimipour, Rouhollah; Strenkert, Daniela; Neupert, Juliane; Schroda, Michael; Merchant, Sabeeha S.; Bock, Ralph
• Is Part Of: Plant journal. Volume 84:Number 4(2015:Nov.)
• Page Start: 704
• Page End: 717
• Publication Date: 2015-10-16
• Subjects: Chlamydomonas reinhardtii -- codon usage -- GC content -- translation -- RNA stability -- epigenetics -- histone modification; Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.13033
• Languages: English
• ISSNs: 0960-7412

Abstract

Summary: The efficiency of gene expression in all organisms depends on the nucleotide composition of the coding region. GC content and codon usage are the two key sequence features known to influence gene expression, but the underlying molecular mechanisms are not entirely clear. Here we have determined the relative contributions of GC content and codon usage to the efficiency of nuclear gene expression in the unicellular green alga Chlamydomonas reinhardtii . By comparing gene variants that encode an identical amino acid sequence but differ in their GC content and/or codon usage, we show that codon usage is the key factor determining translational efficiency and, surprisingly, also mRNA stability. By contrast, unfavorable GC content affects gene expression at the level of the chromatin structure by triggering heterochromatinization. We further show that mutant algal strains that permit high‐level transgene expression are less susceptible to epigenetic transgene suppression and do not establish a repressive chromatin structure at the transgenic locus. Our data disentangle the relationship between GC content and codon usage, and suggest simple strategies to overcome the transgene expression problem in Chlamydomona s. Significance Statement: GC content and codon usage are both known to influence gene expression, but the underlying mechanisms are unclear.. Here we show that codon usage is the key factor that determines translational efficiency and, surprisingly also mRNA stability, thus providing strategies for optimizing transgene expression.