Evolution of RLSB a nuclear-encoded S1 domain RNA binding protein associated with post-transcriptional regulation of plastid-encoded rbcL mRNA in vascular plants

摘要

BackgroundRLSB, an S-1 domain RNA binding protein of Arabidopsis, selectively binds rbcL mRNA and co-localizes with Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) within chloroplasts of C3 and C4 plants. Previous studies using both Arabidopsis (C3) and maize (C4) suggest RLSB homologs are post-transcriptional regulators of plastid-encoded rbcL mRNA. While RLSB accumulates in all Arabidopsis leaf chlorenchyma cells, in C4 leaves RLSB-like proteins accumulate only within Rubisco-containing bundle sheath chloroplasts of Kranz-type species, and only within central compartment chloroplasts in the single cell C4 plant Bienertia. Our recent evidence implicates this mRNA binding protein as a primary determinant of rbcL expression, cellular localization/compartmentalization, and photosynthetic function in all multicellular green plants. This study addresses the hypothesis that RLSB is a highly conserved Rubisco regulatory factor that occurs in the chloroplasts all higher plants.