Article Figures & Data
Figures
- Fig. 1.
Schematic drawing of the organization of arginine biosynthetic genes in T. thermophilus. The genes involved in arginine biosynthesis are: argF (ornithine carbamoyltransferase), argC(N-acetyl-gamma-glutamyl-phosphate reductase), andargJ (glutamate N-acetyltransferase). Other ORFs encode proteins with unknown functions. Arrows show the direction and starting points of transcription. The number of nucleotides present between each pair of ORFs is indicated. A putative rho-independent terminator is present between ORF4 and ORF5. The deduced C-terminal amino acid sequence of ORF4 is shown; the stop codon is indicated by an asterisk.
- Fig. 2.
(A) Primer extension mapping of the transcriptional starting point of the T. thermophilus ORF4 region. Equal amounts (about 50,000 cpm) of 5′-end-labeled 20-mer primer were mixed with 100 μg of RNA extracted from cultures grown in minimal medium (1) or supplemented with arginine (2). After precipitation and hybridization the extension reaction was performed. The position of the transcript is indicated by the arrow; the sequence shown is of the noncoding strand. Lanes G, A, T, and C represent chain-terminating DNA-sequencing reactions of the noncoding strand with the oligonucleotide also used as a primer in the primer extension experiment. (B) Nucleotide and deduced amino acid sequences of a portion of the T. thermophilus ORF4 gene and its promoter region. The arrow pointing downward indicates the transcriptional start site. Also, −35 and −10 promoter sequences are underlined and in bold type. A putative ribosome binding site is indicated by bold letters. The underlined amino acids of ORF4 are identical to the signal sequence of seven proteins of the OmpA family (E coli,Salmonella enterica serovar Typhimurium, B. subtilis, Pseudomonas luteolum, Serratia marcescens, Enterobacter aerogenes, and Shigella dysenteriae).
- Fig. 3.
(A) S1 nuclease mapping of the transcriptional starting point of the argF region. Equal amounts (50,000 cpm) of the 5′-end-labeled 150-bp PCR fragment containing the promoter region ofargF were hybridized with RNA extracted from cultures grown in minimal medium (lane 1) and minimal medium supplemented with arginine (lane 2). After precipitation and hybridization, S1 nuclease activity proceeded. The position of the transcript is indicated by the arrows; the sequence shown is of the noncoding strand. Lanes G, A, T, and C represent chain-terminating DNA-sequencing reactions of the noncoding strand. (B) Nucleotide and deduced amino acid sequences of a portion of the T. thermophilus argF gene and its promoter region. The arrows indicate the transcriptional start sites. Also, −35 and −10 promoter sequences are indicated and in bold type. Sequences showing similarity to the E. coli consensus Arg box are underlined. Boxed sequences were protected from DNase I treatment.
- Fig. 4.
Mobility shift experiments for the Thermus argF promoter region with E. coli ArgR andB. stearothermophilus AhrC in the absence (A) and presence (B) of arginine. Lanes l, no added protein; lanes 2, argFpromoter fragment incubated with B. stearothermophilus AhrC; lanes 3, argF promoter fragment incubated with E. coli ArgR.
- Fig. 5.
DNase I footprinting of the 210-bp fragment of theThermus argF promoter region protected by the E. coli arginine repressor. Lanes: G, A, T, and C, sequencing ladders; 1, DNase I reference ladder (without E. coli ArgR); 2, DNase I treatment in the presence of E. coli ArgR. The approximately 29-bp-long protected stretch is indicated by a bar.
- Fig. 6.
(A) Sequences at the 3′ ends of Thermus andE. coli 16S rRNAs. The region of the 16S RNA molecule complementary to sequences downstream of the AUG start codon of severalThermus and E. coli genes is indicated by boxed nucleotides. (B) Examples of “downstream boxes” in genes fromThermus. Sequences complementary to the region of 16S rRNA shown above are in bold type and underlined. The SD sequence is underlined, and the start codon is indicated by a grey box throughout.
