Disease relevance of rbcL

• Deletion experiments show that the larger sls is essential for producing the native 3' end of rbcL mRNA in E. coli [1].
• Tobacco (Nicotiana tabacum) plants were transformed with plastid DNA that contained the rbcL gene from either sunflower (Helianthus annuus) or the cyanobacterium Synechococcus PCC6301, along with a selectable marker [2].

High impact information on rbcL

• Ribulose bisphosphate carboxylase (Rubisco) is localized in the chloroplasts of photosynthetic eukaryotic cells and is composed of small subunits (SS) and large subunits (LS) coded for by nuclear rbcS and chloroplast rbcL genes, respectively [3].
• Consistent with a primary restriction at translation, fewer rbcL mRNAs are associated with polysomes of normal size and more are free or are associated with only a few ribosomes in the antisense plants [3].
• The conserved plastid localization of rbcL suggests that biosynthesis of the large subunit of ribulose-1,5-bisphosphate carboxylase [Rubisco; 3-phospho-D-glycerate carboxy-lyase (dimerizing), EC 4.1.1.39] in chloroplasts is required to obtain functional enzyme [4].
• First, we deleted the rbcL gene from the tobacco plastid genome by targeted insertion of a selectable aadA gene encoding spectinomycin resistance [4].
• Relocation of the plastid rbcL gene to the nucleus yields functional ribulose-1,5-bisphosphate carboxylase in tobacco chloroplasts [4].

Biological context of rbcL

• Intact open reading frames are present in two species (O. corymbosa and O. fasciculata), whereas the remaining species (O. cernua and O. ramosa) have rbcL pseudogenes [5].
• Species of Orobanche have either had recent photosynthetic ancestors, implying multiple independent losses of photosynthesis in this genus, or the rbcL gene may serve an unknown function in some nonphotosynthetic plants [5].
• Comparison of rbcL 3'-UTR sequences for Nicotiana, Ipomoea, Cuscuta, and Orobanche reveal that nucleotide sequences from parasitic plants have regions capable of forming stem-loop structures, but 56-69 nt are deleted upstream of the stem-loop in the parasitic plants compared to their photosynthetic relatives [5].
• Sequences for rbcL 5'-UTRs from species of Orobanche have few changes in the promoter and ribosome binding sites compared to photosynthetic higher plants [5].
• The rbcL coding region was then inserted into an expression cassette and introduced into the nuclear genome of these plants by Agrobacterium-mediated transformation [4].

Anatomical context of rbcL

• Unlike the available set of homoplasmic knockout mutants in 25 plastid genes, the rbcL deletion mutant isolated here is readily transformed with the efficient aadA marker gene [6].

Associations of rbcL with chemical compounds

• Our results show that the mRNA levels of chloroplast rbcL gene increase in cytokinin-type transgenic tobacco plants as compared with untransformed plants [7].
• The kan gene from the bacterial transposon Tn5, encoding neomycin phosphotransferase (NPTII), was placed under control of plastid expression signals and cloned between rbcL and ORF512 plastid gene sequences to target the insertion of the chimeric gene into the plastid genome [8].
• Targeted gene replacement in plastids was used to explore whether the rbcL gene that codes for the large subunit of ribulose-1, 5-bisphosphate carboxylase/oxygenase, the key enzyme of photosynthetic CO2 fixation, might be replaced with altered forms of the gene [2].
• Although rbcL expression in plants exposed to UV-A was 50% less in the phyA mutant relative to wild type, blue light-induced rbcL expression was not significantly affected in the phyA, phyB, and cry1 mutants [9].

Analytical, diagnostic and therapeutic context of rbcL

• Sequence analysis of non-functional rbcL-related sequences in DeltarbcL plants indicated an extra-plastidic origin [6].
• The plasmid rbcL gene of the hemiparasite Melampyrum pratense and the autotroph Digitalis purpurea both from the Scrophulariaceae were cloned by PCR amplification and then sequenced [10].
• These findings are compatible with results from Western blotting analysis, where no Rubisco large subunit was detectable, and with the lack of Rubisco activity in crude extracts of C. reflexa [11].

References