A tobacco chloroplast DNA sequence possibly coding for a polypeptide similar to E. coli RNA polymerase beta-subunit

DNA sequencing has revealed a long open reading frame (ORF) in the large single-copy region of tobacco chloroplast DNA. This ORF consists of 1070 codons and its deduced amino acid sequence shows about 39% homology to that of the beta-subunit of E. coli RNA polymerase. This finding raises a possibility that some of the chloroplast RNA polymerase subunits are coded for by the chloroplast genome.     

A missense mutation in the gene coding for ribosomal protein S17 (rpsQ) leading to ribosomal assembly defectivity in Escherichia coli.

Summary The conditionally lethal mutation, 286lmis, has been mapped inside the ribosomal protein gene cluster at 72 minutes on the Escherichia coli chromosome and was found to cotransduce at 97% with rpsE (S5). The 2861mis mutation leads to thermosensitivity and impaired assembly in vivo of 30S ribosomal particles at 42°C. The strain carrying the mutation has an altered S17 ribosomal protein; the mutational alteration involves a replacement of serine by phenylalanine in protein S17. Spontaneous reversion to temperature independence can restore the normal assembly in vivo of 30S ribosomal subunits at 42°C and the normal chromatographical sehaviour of the S17 ribosomal protein in vitro. We conclude therefore that the 2861mis mutation affects the structural gene for protein S17 (rpsQ).     

The DNA sequence of the gene rpsA of Escherichia coli coding for ribosomal protein S1.

The DNA sequence of the gene rpsA as well as of its neighboring regions has been determined using the dideoxyribonucleotide method. It was found that there is an "open-reading-frame" of 350 bp which precedes the gene rpsA. Furthermore, an extensive internal repeats of nucleotide sequence have been found in this gene.     

Nucleotide sequence of a Euglena gracilis chloroplast gene coding for the 16S rRNA: homologies to E. coli and Zea mays chloroplast 16S rRNA

The nucleotide sequence of 16S rDNA from Euglena gracilis chloroplasts has been determined representing the first complete sequence of an algal chloroplast rRNA gene. The structural part of the 16S rRNA gene has 1491 nucleotides according to a comparative analysis of our sequencing results with the published 5'- and 3'-terminal "T1-oligonucleotides" from 16S rRNA from E. gracilis. Alignment with 16S rDNA from Zea mays chloroplasts and E. coli reveals 80 to 72% sequence homology, respectively. Two deletions of 9 and 23 nucleotides are found which are identical in size and position with deletions observed in 16S rDNA of maize and tobacco chloroplasts and which seem to be characteristic for all chloroplast rRNA species. We also find insertions and deletions in E. gracilis not seen in 16S rDNA of higher plant chloroplasts. The 16S rRNA sequence of E. gracilis chloroplasts can be folded by base pairing according to the general 16S rRNA secondary structure model.     

A conditionally lethal mutation of Escherichia coli affecting the gene coding for ribosomal protein S2 (rpsB).

Localized P1 mutagenesis has been used to isolate conditionally lethal mutations in the four-minute region of the Escherichia coli genome. One such mutation, ts25, has been mapped at about 3.7 minutes between the popC and dapD genes. This mutation leads to thermosensitivity of growth and impaired in vivo assembly of 30 S ribosomal subunits at 42 °C. The strain carrying the mutation has an altered S2 ribosomal protein as judged by (1) its inability to maintain stable complex with the ribosome under mild washing conditions and (2) its altered electrophoretic mobility.Spontaneous reversion to temperature independence can restore both the normal assembly in vivo of 30 S ribosomal subunits at 42 °C and the normal electrophoretic behaviour of the S2 ribosomal protein in vitro.We conclude therefore that the ts25 mutation affects the structural gene for ribosomal protein S2 (rpsB).     

A novel plant nuclear gene encoding chloroplast ribosomal protein S9 has a transit peptide related to that of rice chloroplast ribosomal protein L12

We have cloned a novel nuclear gene for a ribosomal protein of rice and Arabidopsis that is like the bacterial ribosomal protein S9. To determine the subcellular localization of the gene product, we fused the N-terminal region and green fluorescent protein and expressed it transiently in rice seedlings. Localized fluorescence was detectable only in chloroplasts, indicating that this nuclear gene encodes chloroplast ribosomal protein S9. The N-terminal region of rice ribosomal protein S9 was found to have a high sequence similarity to the transit peptide region of the rice chloroplast ribosomal protein L12, suggesting that these transit peptides have a common lineage.     

Nucleotide sequence of the Aspergillus nidulans mitochondrial gene coding for the small ribosomal subunit RNA: homology to E. coli 16S rRNA.

The complete primary structure of the 1437 bp gene coding for mitochondrial 15S rRNA and its flanking regions was determined by Maxam-Gilbert sequencing of cloned HindIII fragment H3 of A. nidulans mtDNA. The gene product reveals significant homology (59%) to E. coli 16S rRNA, and the potential secondary structures of both rRNA molecules are very similar, except that the hairpin structures 7, 8 and 30 of the Brimacombe 16S rRNA model are deleted, and that two sequences of 8 and 31 nucleotides are inserted in the mitochondrial species.     

A novel yeast gene coding for a putative protein kinase

A yeast gene termed YKR2 coding for a putative protein kinase was isolated using the cloned cDNA for rabbit protein kinase C as a hybridization probe. The encoded protein YKR2, containing 677 amino acids, shows about 40% sequence identity in the kinase region to a family of serine/threonine-specific protein kinases from various species.     

Evidence that E. coli ribosomal protein S13 has two separable functional domains involved in 16S RNA recognition and protein S19 binding.

We have found that E. coli ribosomal protein S13 recognizes multiple sites on 16S RNA. However, when protein S19 is included with a mixture of proteins S4, S7, S8, S16/S17 and S20, the S13 binds to the complex with measurably greater strength and with a stoichiometry of 1.5 copies per particle. This suggests that the protein may have two functional domains. We have tested this idea by cleaving the protein into two polypeptides. It was found that one of the fragments, composed of amino acid residues 84-117, retained the capacity to bind 16S RNA at multiple sites. Protein S19 had no affect on the strength or stoichiometry of the binding of this fragment. These data suggest that S13 has a C-terminal domain primarily responsible for RNA recognition and possibly that the N-terminal region is important for association with protein S19.