ABSTRACT
The complete nucleotide sequence is presented for pUH24, the small plasmid of Synechococcus sp. PCC 7942. pUH24 consists of 7835bp and has a G + C content of 59%. The distribution of translation start and stop codons in the sequence allows 36 open reading frames that potentially encode polypeptides of 50 or more amino acids. We postulate that eight of these open reading frames are actual coding sequences. A region has been identified, by experiment, that contains two functions, designated pmaA and pmaB, involved in the segregational stability of the plasmid. The minimal region of pUH24 fully capable of supporting autonomous replication consists of a 3.6kb DNA fragment, which is almost entirely occupied by two overlapping genes most likely coding for essential replication proteins (repA and repB).
Subject(s)
Cyanobacteria/genetics , DNA Replication , DNA, Bacterial , Plasmids/genetics , Amino Acid Sequence , Bacterial Proteins , Base Sequence , DNA, Bacterial/biosynthesis , DNA, Bacterial/genetics , Genetic Vectors , Molecular Sequence Data , Open Reading Frames , Protein Biosynthesis , Restriction Mapping , Transcription, GeneticABSTRACT
We have isolated and analyzed a pre-ferredoxin gene from Arabidopsis thaliana. This gene encodes a 148 amino acid precursor protein including a chloroplast transit peptide of 52 residues. Southern analysis shows the presence of a single copy of this ferredoxin (Fd) gene in the A. thaliana genome. Its expression is tissue-specific and positively affected by light. Response times, both to dark and light conditions, are remarkably rapid. A chimeric gene consisting of a 1.2 kb Fd promoter fragment fused to the beta-glucuronidase reporter gene was transferred to tobacco. This fusion gene is expressed in a tissue-specific way; it shows high levels of expression in green leaves, as compared to root tissue.
Subject(s)
Ferredoxins/genetics , Plants/genetics , Amino Acid Sequence , Base Sequence , Cloning, Molecular , DNA/genetics , Ferredoxins/metabolism , Gene Expression , Genetic Engineering , Molecular Sequence Data , Plant Proteins/genetics , Plant Proteins/metabolism , Plants, Toxic , Promoter Regions, Genetic , Protein Precursors/genetics , Protein Precursors/metabolism , Restriction Mapping , Tissue Distribution , Nicotiana/genetics , Nicotiana/metabolismABSTRACT
A genomic clone encoding the plastocyanin precursor was isolated from an Arabidopsis thaliana lambda EMBL3 library, with the help of a heterologous hybridization probe. The nucleotide (nt) sequence encoding the 171-amino acid precursor protein and 650 bp of the 5'-flanking region were determined. S1 nuclease mapping showed the Arabidopsis coding region to be uninterrupted and the transcript to possess an untranslated leader of approx. 30 nt. The 5' region of the gene contains a 25-bp direct repeat at a distance of 300 bp upstream from the ATG start codon. Southern analysis of several genomic digests shows the presence of a single copy of the plastocyanin gene in the Arabidopsis genome. In vitro synthesized pre-plastocyanin was used in import experiments with isolated pea chloroplasts. Plastocyanin was correctly directed to the thylakoid lumen and processed to the mature size. A clear single processing intermediate, as was found with the import of Silene pratensis pre-plastocyanin, seems to be absent.
