Gene clusters for ribosomal proteins in the mitochondrial genome of a liverwort,Marchantia polymorpha

Abstract

We detected 16 genes for ribosomal proteins in the complete sequence of the mitochondrial DNA from a liverwort, Marchantia polymorpha. The genes formed two major clusters, rps12-rps7 and rps10-rpl2-rps19-rps3-rpl16-rpl5- rps14-rps8- rpl6-rps13-rps11-rps1, very similar in organization to Escherichia coli ribosomal protein operons (str and S10-spc-alpha operons, respectively). In contrast, rps2 and rps4 genes were located separately in the liverwort mitochondrial genome (the latter was part of the alpha operon in E. coli). Furthermore, several ribosomal proteins encoded by the liverwort mitochondrial genome differed substantially in size from their counterparts in E. coli and liverwort chloroplast.

Identification of the yeast nuclear gene for the mitochondrial homologue of bacterial ribosomal protein L16

“…While this extension sequence might contain the mitochondrial targeting information for the yeast mitochondrial protein, there is no apparent need for such a targeting sequence in a polypeptide translated within maize mitochondria. Indeed, it has been argued that translation of L16 in the plant mitochondria initiates at a GUG valine codon (31,32). For example, the amino-terminal residue of the liverwort (Marchantia polymorpha) sequence shown in Figure 4 is assumed to be a methionine encoded by a GUG initiation codon because there are no suitable candidate AUG initiation codons (31).…”

“…Indeed, it has been argued that translation of L16 in the plant mitochondria initiates at a GUG valine codon (31,32). For example, the amino-terminal residue of the liverwort (Marchantia polymorpha) sequence shown in Figure 4 is assumed to be a methionine encoded by a GUG initiation codon because there are no suitable candidate AUG initiation codons (31). If L16 translation in maize and Petunia initiates at the identical GUG valine codon instead of at an upstream AUG, then these proteins would also lack N-terminal extensions and their N-termini would align with that of E.coli L16.…”

Transfer of rps10 from the mitochondrion to the nucleus in Arabidopsis thaliana: evidence for RNA‐mediated transfer and exon shuffling at the integration site

“…One ribosomal protein gene (varl) is present on the yeast mitochondrial genome [3], while the rest of the expected 60-80 proteins is encoded in the nucleus and imported from the cytosol into the organelle (for review see [4]). In Marchantiapolymorpha sixteen genes coding for ribosomal proteins have been identified on the mitochondrial genome from homology to their bacterial counterparts [5]. The organization of ribosomal protein genes in the liverwort is similar to the situation found in E. coli [6] but differs in higher plants where the genes are scattered far apart in the genome [7].…”

“…Ten independant cDNA clones were found that were polyadenylated and showed high similarity to the mitochondrial rpslO sequences of potato [10], pea [9], and Marchantia [5]. [5], Pisum sativum (P. sativum) [9], and Solanum tuberosum (S. tubersosum) [10], the cyanellar sequence of Cyanophora paradoxa (C. paradoxa) [24], the cyanobacterial sequence of Spirulina platensis (S. platensis) [25], and the eubacterial sequence of Escherichia coil (E. coli) [26] are shown.…”

“…[5], Pisum sativum (P. sativum) [9], and Solanum tuberosum (S. tubersosum) [10], the cyanellar sequence of Cyanophora paradoxa (C. paradoxa) [24], the cyanobacterial sequence of Spirulina platensis (S. platensis) [25], and the eubacterial sequence of Escherichia coil (E. coli) [26] are shown. Homologous amino acids between the different RPSIO polypeptides are highlighted by inverse contrast.…”