A tellurite-resistance genetic determinant from phytopathogenic pseudomonads encodes a thiopurine methyltransferase: evidence of a widely-conserved family of methyltransferases

Cournoyer, Benoît; Watanabe, Satoshi; Vivian, Alan

doi:10.1016/s0167-4781(98)00020-7

Cited by 56 publications

(61 citation statements)

References 18 publications

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“…Thus, a putative role of SUMT in K 2 TeO 3 resistance would be the utilization of Te as a substrate and to catalyze the transfer of methyl groups from SAM to the metalloid. In this context, some work from other authors has indicated that the gene products of the tpm and tehB genes from Pseudomonas syringae and E. coli, respectively, are able to biomethylate tellurium (Cournoyer et al, 1998;Liu et al, 2000). Unfortunately, we were unable to detect the genesis of methylated tellurium derivatives in the headspace of cells cultured in the presence of tellurite or tellurate.…”

Section: Cobacontrasting

confidence: 59%

Site-Directed Mutagenesis as a Tool for Unveiling Mechanisms of Bacterial Tellurite Resistance

Pérez-Donoso¹,

Vásquez²

2013

Genetic Manipulation of DNA and Protein - Examples From Current Research

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Section: Cobacontrasting

confidence: 59%

Site-Directed Mutagenesis as a Tool for Unveiling Mechanisms of Bacterial Tellurite Resistance

Pérez-Donoso¹,

Vásquez²

2013

Genetic Manipulation of DNA and Protein - Examples From Current Research

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“…In these reports, Te 2 (CH 3 ) 2 was considered to be the odorous ingredient, although other compounds of tellurium, selenium, and sulfur also have this property. A study of a nonhomologous tellurite resistance gene (tpm) from Pseudomonas syringae pathovar pisi provided evidence that methylation might be involved in tellurite resistance (11). The chemical nature of the methylated tellurium product was not determined in this study.…”

mentioning

confidence: 82%

“…tpm encodes a methyltransferase that catalyzes S-adenosyl-L-methionine (SAM) methylation of 6-mercaptopurine, a substrate for human thiopurine methyltransferase. It was assumed that tellurite is also a substrate for this enzyme (11).…”

mentioning

confidence: 99%

Escherichia coli TehB Requires S -Adenosylmethionine as a Cofactor To Mediate Tellurite Resistance

et al. 2000

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The Escherichia coli chromosomal determinant for tellurite resistance consists of two genes (tehA and tehB) which, when expressed on a multicopy plasmid, confer resistance to K 2 TeO 3 at 128 g/ml, compared to the MIC of 2 g/ml for the wild type. TehB is a cytoplasmic protein which possesses three conserved motifs (I, II, and III) found in S-adenosyl-L-methionine (SAM)-dependent non-nucleic acid methyltransferases. Replacement of the conserved aspartate residue in motif I by asparagine or alanine, or of the conserved phenylalanine in motif II by tyrosine or alanine, decreased resistance to background levels. Our results are consistent with motifs I and II in TehB being involved in SAM binding. Additionally, conformational changes in TehB are observed upon binding of both tellurite and SAM. The hydrodynamic radius of TehB measured by dynamic light scattering showed a ϳ20% decrease upon binding of both tellurite and SAM. These data suggest that TehB utilizes a methyltransferase activity in the detoxification of tellurite.Tellurite (TeO 3 2Ϫ ) resistance, which is found in many microorganisms (37), is carried on plasmids of IncHI, IncHII, and IncP incompatibility groups (3, 36, 39) and/or on chromosomes (9, 10, 29, 33). Tellurite resistance (Te r ) determinants are very diverse, and at least five different determinants have been identified (37). Te r determinants are unrelated, and probably different resistance mechanisms are involved. Except for that encoded by the Pseudomonas syringae tpm gene, Te r mechanisms are not clearly understood. tpm encodes a methyltransferase that catalyzes S-adenosyl-L-methionine (SAM) methylation of 6-mercaptopurine, a substrate for human thiopurine methyltransferase. It was assumed that tellurite is also a substrate for this enzyme (11).The Te r determinant tehAB, an operon located at 32.3 min on the Escherichia coli K-12 chromosome (38), encodes proteins of 330 (TehA) and 197 (TehB) amino acids. TehA is a membrane protein with 10 transmembrane segments, whereas TehB is a soluble protein. The closest homologues of these two genes are found in Haemophilus influenzae (15).A sequence search performed with the BLAST program (National Center for Biotechnology Information), followed by alignment analysis with the Genetics Computer Group software package (University of Wisconsin) (12), demonstrated that TehB displays some amino acid sequence similarity to many SAM-dependent non-nucleic acid methyltransferases. These proteins have three shared motifs, and the TehB proteins show homologies within all regions with comparable sequence interval distances (Fig.

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“…In addition, there are a number of unclassified plasmids which confer Te r on their hosts (Taylor & Summers, 1979). Te r determinants found on chromosomes include the tehAtehB operon at 32n3 min of the E. coli chromosome (Taylor et al, 1994), tmp of Pseudomonas syringae (Cournoyer et al, 1998) and the trgAB genes of Rhodobacter sphaeroides (O'Gara et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

Tellurite-mediated thiol oxidation in Escherichia coli

1999

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2N3 ), is toxic to most micro-organisms, particularly Gram-negative bacteria. The mechanism of tellurite toxicity is presently unknown. Many heavy metals and oxyanions, including tellurite, interact with reduced thiols (RSH). To determine if tellurite interaction with RSH groups is involved in the toxicity mechanism, the RSH content of Escherichia coli cultures was assayed. After exposure to tellurite, cells were harvested and lysed in the presence of the RSH-specific reagent 5,5'-dithiobis(2-nitrobenzoic acid). Upon exposure of tellurite-susceptible cells to TeO

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A tellurite-resistance genetic determinant from phytopathogenic pseudomonads encodes a thiopurine methyltransferase: evidence of a widely-conserved family of methyltransferases

Cited by 56 publications

References 18 publications

Site-Directed Mutagenesis as a Tool for Unveiling Mechanisms of Bacterial Tellurite Resistance

Site-Directed Mutagenesis as a Tool for Unveiling Mechanisms of Bacterial Tellurite Resistance

Escherichia coli TehB Requires S -Adenosylmethionine as a Cofactor To Mediate Tellurite Resistance

Tellurite-mediated thiol oxidation in Escherichia coli

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