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Cloning and characterization of tRNA (m1A58) methyltransferase (TrmI) from Thermus thermophilus HB27, a protein required for cell growth at extreme temperatures.

ABSTRACT: N1-methyladenosine (m1A) is found at position 58 in the T-loop of many tRNAs. In yeast, the formation of this modified nucleoside is catalyzed by the essential tRNA (m1A58) methyltransferase, a tetrameric enzyme that is composed of two types of subunits (Gcd14p and Gcd10p). In this report we describe the cloning, expression and characterization of a Gcd14p homolog from the hyperthermophilic bacterium Thermus thermophilus. The purified recombinant enzyme behaves as a homotetramer of 150 kDa by gel filtration and catalyzes the site- specific formation of m1A at position 58 of the T-loop of tRNA in the absence of any other complementary protein. S-adenosylmethionine is used as donor of the methyl group. Thus, we propose to name the bacterial enzyme TrmI and accordingly its structural gene trmI. These results provide a key evolutionary link between the functionally characterized two-component eukaryotic enzyme and the recently described crystal structure of an uncharacterized, putative homotetrameric methyltransferase Rv2118c from Mycobacterium tuberculosis. Interest ingly, inactivation of the T.thermophilus trmI gene results in a thermosensitive phenotype (growth defect at 80 degrees C), which suggests a role of the N1-methylation of tRNA adenosine-58 in adaptation of life to extreme temperatures.

SUBMITTER: Droogmans L

PROVIDER: S-EPMC153742 | biostudies-literature | 2003 Apr

REPOSITORIES: biostudies-literature

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Cloning and characterization of tRNA (m1A58) methyltransferase (TrmI) from Thermus thermophilus HB27, a protein required for cell growth at extreme temperatures.

Droogmans Louis L Roovers Martine M Bujnicki Janusz M JM Tricot Catherine C Hartsch Thomas T Stalon Victor V Grosjean Henri H

Nucleic acids research 20030401 8

N1-methyladenosine (m1A) is found at position 58 in the T-loop of many tRNAs. In yeast, the formation of this modified nucleoside is catalyzed by the essential tRNA (m1A58) methyltransferase, a tetrameric enzyme that is composed of two types of subunits (Gcd14p and Gcd10p). In this report we describe the cloning, expression and characterization of a Gcd14p homolog from the hyperthermophilic bacterium Thermus thermophilus. The purified recombinant enzyme behaves as a homotetramer of 150 kDa by ge ...[more]

PMID: 12682365

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Project description:BackgroundPenicillin acylases (PACs) are enzymes of industrial relevance in the manufacture of β-lactam antibiotics. Development of a PAC with a longer half-life under the reaction conditions used is essential for the improvement of the operational stability of the process. A gene encoding a homologue to Escherichia coli PAC was found in the genome of the thermophilic bacterium Thermus thermophilus (Tth) HB27. Because of the nature of this PAC and its complex maturation that is crucial to reach its functional heterodimeric final conformation, the overexpression of this enzyme in a heterologous mesophilic host was a challenge. Here we describe the purification and characterization of the PAC protein from Tth HB27 overexpressed in Escherichia coli.ResultsFusions to a superfolder green fluorescent protein and differential membrane solubilization assays indicated that the native enzyme remains attached through its amino-terminal end to the outer side of the cytoplasmic membrane of Tth cells. In order to overexpress this PAC in E. coli cells, a variant of the protein devoid of its membrane anchoring segment was constructed. The effect of the co-expression of chaperones and calcium supplementation of the culture medium was investigated. The total production of PAC was enhanced by the presence of DnaK/J and GrpE and even more by trigger factor and GroEL/ES. In addition, 10 mM calcium markedly improved both PAC specific and volumetric activities. Recombinant PAC was affinity-purified and proper maturation of the protein was confirmed by SDS-PAGE and MALDI-TOF analysis of the subunits. The recombinant protein was tested for activity towards several penicillins, cephalosporins and homoserine lactones. Hydrophobic acyl-chain penicillins were preferred over the rest of the substrates. Penicillin K (octanoyl penicillin) was the best substrate, with the highest specificity constant value (16.12 mM-1.seg-1). The optimum pH was aprox. 4 and the optimum temperature was 75 °C. The half-life of the enzyme at this temperature was 9.2 h.ConclusionsThis is the first report concerning the heterologous expression of a pac gene from a thermophilic microorganism in the mesophilic host E. coli. The recombinant protein was identified as a penicillin K-deacylating thermozyme.

Dataset Information

Cloning and characterization of tRNA (m1A58) methyltransferase (TrmI) from Thermus thermophilus HB27, a protein required for cell growth at extreme temperatures.

Publications

Cloning and characterization of tRNA (m1A58) methyltransferase (TrmI) from Thermus thermophilus HB27, a protein required for cell growth at extreme temperatures.

Similar Datasets

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