Analysis of the Methionine Biosynthetic Pathway in the Extremely Thermophilic Eubacterium Thermus thermophilus

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概要

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• Four DNA fragments that could rescue the mutations of four Met^- mutants were cloned from Thermus thermophilus HB27 and their complete nucleotide sequences were determined. Two of the four fragments respectively contained the greater parts of the metF and metH genes, the predicted amino acid sequences of which showed identities of 30.8% and 32.7% with 5.10-methylenetetrahydrofolate reductase (EC 1.7.99.5) and vitamin B_<12>-dependent homocysteine transmethylase (EC 2.1.1.13) of Escherichia coil. The other two DNA fragments, which overlapped one another, contained two open reading frames whose predicted amino acid sequences were respectively similar to those of O-acetylhomoserine sulfhydrylase (EC 4.2.99.10, the product of the MET17 gene) and homoserine O-acetyltransferase (EC 2.3.1.31, the product of the MET2 gene) of Saccharomyces cerevisiae. The metF, metH, MET2, and MET17 genes of T. thermophilus were disrupted by introducing the heat-stable kanamycin nucleotidyltransferase gene into the genome. Each transformant showed methionine auxotrophy. Both the MET2- and MET17-disrupted mutants could grow in a minimal medium containing homocysteine but not in the same medium containing succinylhomoserine or cystathionine. In contrast, the metF- and metH-disrupted mutants could not grow in the minimal medium containing homocysteine. These results suggest that in T. thermophilus, homoserine is directly converted to homocysteine via O-acetylhomoserine and that homocysteine is methylated to syuthesize methionine.

• 公益社団法人日本生物工学会の論文
• 2000-09-25

著者

• Hoshino T

  Waseda Univ. Tokyo Jpn

• Hoshino Takayuki

  Institute Of Applied Biochemistry University Of Tsukuba

• Kosuge Takehide

  Institute Of Applied Biochemistry University Of Tsukuba

• GAO DAI

  Institute of Applied Biochemistry, University of Tsukuba

• Gao Dai

  Institute Of Applied Biochemistry University Of Tsukuba

関連論文

• Development of Expression Vectors for Thermus thermophilus
• Role of the DNA Sequence Downstream of the Bacillus subtilis hut Promoter in Regulation of the hut Operon
• Determination of the Transcriptional Initiation Sites of the Kanamycin Resistance Genes of pUB110 and pTHN1
• Purification and Properties of NAD-Linked 1,2-Butanediol Dehydrogenase from Rhodococcus sp. strain TB-42
• Unusual Transcription Regulation of the niaD Gene under Anaerobic Conditions Supporting Fungal Ammonia Fermentation
• The Entire Population of Thermus thermophilus Cells Is Always Competent at Any Growth Phase
• Overproduction of Carotenoids in Thermus thermophilus
• Isolation and Partial Characterization of Carotenoid Underproducing and Overproducing Mutants from an Extremetly Thermophilic Thermus thermophilus HB27
• Fusion with Ribosomal Protein L32 Increased the in vivo Thermostability of Kanamycin Nucleotidyltransferase in Thermus thermophilus
• The α-Aminoadipate Pathway for Lysine Biosynthesis Is Widely Distributed among Thermus Strains
• Cloning and Sequence Analysis of Fumarase and Superoxide Dismutase Genes from an Extreme Thermophile Thermus thermophilus HB27
• Efficient Selection for Thermostable Protease in Themus thermophilus
• Plasmid Marker Rescue Transformation in Thermus thermophilus
• Analysis of the Methionine Biosynthetic Pathway in the Extremely Thermophilic Eubacterium Thermus thermophilus

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