Presentation Title

Oxygen evolving enhancer protein 1 mRNA accumulation is regulated by yellow light in Chlamydomonas reinhardtii

Faculty Mentor

Laura Arce, Amybeth Cohen

Start Date

17-11-2018 12:30 PM

End Date

17-11-2018 2:30 PM

Location

HARBESON 3

Session

POSTER 2

Type of Presentation

Poster

Subject Area

biological_agricultural_sciences

Abstract

Chlamydomonas reinhardtii is a unicellular green alga that has photosynthetic properties similar to that of higher-ordered plants. It therefore serves as a model organism to study the photosynthetic pathways. A key player in the light reaction of photosynthesis is the D1 protein, which is translated in a light-dependent manner after a set of nuclear-encoded RNA-binding (RB) proteins (RB38, RB47, and RB60) form a complex that interacts with a stem loop structure in the 5’-untranslated region of the psbA mRNA. Both red and blue light were found to induce the expression of the rb38 and rb60 genes, as well as the psbO gene (encodes Oxygen Evolving Enhancer Protein 1) (Alizadeh and Cohen, 2010). Recent research determined that the animal-like cryptochrome (aCRY) in C. reinhardtii is sensitive to red, blue and yellow light and plays a role in regulating gene expression in several biosynthetic and metabolic pathways (Beel et al, 2012). Thus, aCRY may be the photoreceptor that regulates red- and blue-light induced rb and psbO gene expression. Therefore, RT-PCR analysis is being performed to ascertain the role of various light qualities on the induction of these genes. Initial results indicate that yellow light promotes the accumulation of the psbO mRNA. Yellow-, blue- and red-light induction of psbO, psbA, rb38, rb47, and rb60 will be further assessed in C. reinhardtii wild-type, aCRY-knockout, and rescue strains. This work is important as it aims to expand the repertoire of genes regulated by aCRY. It also may further elucidate the light-dependent regulation of photosynthetic gene expression and determine if aCRY is the red-light photoreceptor yet to be identified in C. reinhardtii.

Summary of research results to be presented

RT-PCR analysis indicates that yellow light promotes the accumulation of the psbO mRNA. Interestingly, we show that exposure to yellow light leads to mRNA accumulation increases and decreases over time. Dark grown Chlamydomonas reinhardtii cells exhibited little to no psbO mRNA accumulation. However, an increase in mRNA accumulation was observed when dark grown cells were shifted to yellow light for 20 minutes and remained present after 40 minutes of yellow light exposure. Remarkably, psbO levels decreased after 60 minutes, increased after 90 minutes, and once again decreased upon 120 minutes of yellow light exposure. A light-dependent cyclical response has been ascribed to the the animal-like cryptochrome (aCRY) for biosynthetic, metabolic and other pathways (Beel,et al 2012). The cyclical nature of the psbO response, further supports the hypothesis that the psbO gene may be regulated by this cryptochrome.

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Nov 17th, 12:30 PM Nov 17th, 2:30 PM

Oxygen evolving enhancer protein 1 mRNA accumulation is regulated by yellow light in Chlamydomonas reinhardtii

HARBESON 3

Chlamydomonas reinhardtii is a unicellular green alga that has photosynthetic properties similar to that of higher-ordered plants. It therefore serves as a model organism to study the photosynthetic pathways. A key player in the light reaction of photosynthesis is the D1 protein, which is translated in a light-dependent manner after a set of nuclear-encoded RNA-binding (RB) proteins (RB38, RB47, and RB60) form a complex that interacts with a stem loop structure in the 5’-untranslated region of the psbA mRNA. Both red and blue light were found to induce the expression of the rb38 and rb60 genes, as well as the psbO gene (encodes Oxygen Evolving Enhancer Protein 1) (Alizadeh and Cohen, 2010). Recent research determined that the animal-like cryptochrome (aCRY) in C. reinhardtii is sensitive to red, blue and yellow light and plays a role in regulating gene expression in several biosynthetic and metabolic pathways (Beel et al, 2012). Thus, aCRY may be the photoreceptor that regulates red- and blue-light induced rb and psbO gene expression. Therefore, RT-PCR analysis is being performed to ascertain the role of various light qualities on the induction of these genes. Initial results indicate that yellow light promotes the accumulation of the psbO mRNA. Yellow-, blue- and red-light induction of psbO, psbA, rb38, rb47, and rb60 will be further assessed in C. reinhardtii wild-type, aCRY-knockout, and rescue strains. This work is important as it aims to expand the repertoire of genes regulated by aCRY. It also may further elucidate the light-dependent regulation of photosynthetic gene expression and determine if aCRY is the red-light photoreceptor yet to be identified in C. reinhardtii.