High impact information on psbL

• Distinct cissequences and trans-factor requirements for the psbL and ndhD editing sites indicate an individual recognition mechanism for the editing of plastid initiation codons [1].
• Sequences directing C to U editing of the plastid psbL mRNA are located within a 22 nucleotide segment spanning the editing site [1].
• To identify the RNA segment required for psbL editing, chimeric kanamycin resistance genes were constructed containing psbL deletion derivatives, and tested in vivo for editing in transgenic plants [1].
• To determine if editing may occur in a chimeric mRNA, the N-terminal part of psbL containing the editing site was translationally fused with the aadA and kan bacterial genes [2].
• RNA editing in tobacco chloroplasts leads to the formation of a translatable psbL mRNA by a C to U substitution within the initiation codon [3].

Biological context of psbL

• A C-to-U RNA editing event creates a functional initiation codon for translation of the psbL mRNA in tobacco plastids [4].
• A computer search of the tobacco plastid genome (ptDNA) identified such a putative gRNA, a 14-nucleotide sequence motif that is complementary to the psbL mRNA, including the A nucleotide required to direct the C-to-U change [4].
• Endogenous transcripts of rpoB, psbL and rps14, all of which contain common sequences S1, S2 and S3 5' to NTrpoB C473, NTpsbL C2 and NTrps14 C80, were less edited in transgenic plants that over-express transcripts from NTrpoB C473 transgenes [5].
• The alignment of the psbL nucleotide sequences from ten species shows strong conservation, which is indicative of a functional gene [3].

Anatomical context of psbL

• In tobacco plastids, functional psbL mRNA is created by editing an ACG codon to an AUG translation initiation codon [2].

Associations of psbL with chemical compounds

• Conditions either facilitating oxidation or avoiding reduction of the plastoquinone pool do not affect the Fm(L) level of Delta psbL plants but prevent the appearance of Fm(D) [6].

Other interactions of psbL

• Here, we report the effect of inactivation of psbL on the directional forward electron flow of photosystem II as compared to that of the wild type and the psbJ deletion mutant, which is impaired in PSII electron flow to plastoquinone [Regel et al. (2001) J. Biol. Chem. 276, 41473-41478] [6].
• We conclude that within the -20/-5 region, sequences common to editing sites in the transcripts of rpoB, psbL and rps14 are critical for efficient NTrpoB C473 editing [5].

References