The organization and expression of essential transcription translation component genes in the extremely thermophilic eubacterium Thermotoga maritima.
A 5789-nucleotide-long EcoRI fragment from the genome of Thermotoga maritima, identified by cross-hybridization to L11, L1, L10, and L12 ribosomal protein gene sequences from Escherichia coli, was cloned and sequenced. The fragment encodes five tRNAs (tRNA(met1), anticodon complementary to AUG; tRNA(met2), AUG; tRNA(thr), ACA; tRNA(tyr), UAC; tRNA(trp), UGG), the transcription termination-antitermination factor nusG, the four 50 S subunit ribosomal proteins L11, L1, L10, and L12, and the amino-terminal portion of the RNA polymerase beta subunit protein. The five tRNA genes, the nusG gene, and the L11, L1, L10, and L12 ribosomal protein genes form a complex transcription unit. Transcripts appear to be initiated from an upstream promoter, P1, located in front of the tRNA(met1) gene and from three internal promoters: P2 is located immediately in front of the tRNA(met2) gene; PL10 is near the beginning of the L1-L10 intergenic space, and PL12 is at the end of the L10 gene sequence. The tRNA sequences are excised from the leader regions of the P1- and P2-initiated transcripts. Three putative but potentially important regulatory sequences were identified within this operon: an L1 translational control site, a transcription attenuator, and a strong rho-independent terminator. The strong terminator located distal to the L12 gene overlaps a fifth promoter, P beta, which is used to initiate transcripts of the downstream RNA polymerase beta subunit gene. The T. maritima NusG protein exhibits 43% amino acid sequence identity when aligned to the E. coli protein; the alignment is interrupted by a large 171-amino acid-long insertion into the T. maritima protein after codon 45.
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Canadian Institute for Advanced Research, University of British Columbia, Vancouver.
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D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D001665:Binding Sites; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D015246:Deoxyribonuclease EcoRI; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D016680:Genome, Bacterial; D006089:Gram-Negative Anaerobic Bacteria / Q000235:genetics*; D006358:Hot Temperature; D007438:Introns; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010445:Peptide Elongation Factors / Q000235:genetics*; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D012319:RNA Polymerase II / Q000235:genetics*; D012343:RNA, Transfer / Q000235:genetics*; D015183:Restriction Mapping; D012269:Ribosomal Proteins / Q000235:genetics*; D012270:Ribosomes / Q000378:metabolism; D012689:Sequence Homology, Nucleic Acid; D013728:Terminator Regions, Genetic; D014157:Transcription Factors; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D046911:Macromolecular Substances; C070291:NusG protein, E coli; D010445:Peptide Elongation Factors; D012269:Ribosomal Proteins; D014157:Transcription Factors; D012343:RNA, Transfer; D012319:RNA Polymerase II; D015246:Deoxyribonuclease EcoRI