Isolation and characterization of Escherichia coli mutants affected in aerobic respiration: the cloning and nucleotide sequence of ubiG: Identification of an S-adenosylmethionine-binding motif in protein, RNA, and small-molecule methyltransferases

Wu, Guanghui; Williams, Huw D.; Zamanian, Maryam; Gibson, F.; Poole, Robert K.

doi:10.1099/00221287-138-10-2101

Cited by 71 publications

(60 citation statements)

References 51 publications

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“…1). Motif I is a glycine-rich region agreeing well with the consensus sequence h(D/E)h GxGxG, where h represents a hydrophobic residue and x is any residue (27,46). Motif I is generally followed by an acidic residue on the C-terminal side, about 17 to 19 residues from the motif (27).…”

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confidence: 73%

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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confidence: 73%

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

et al. 2000

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“…The signature UU [DE]xGxGxG (hereafter U designates a bulky aliphatic amino acid residue, and x is any residue) is conserved in most but not all SAMutilizing methyltransferases (Ingrosso et al, 1989;Haydock et al, 1991;Wu et al, 1992). Unexpectedly, this signature was detected in NS5 proteins of all flaviviruses.…”

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confidence: 99%

“…First, this is the only region of detectable similarity among methyltransferases that methylate a wide variety of acceptors but all use the same donor of the methyl group, SAM. Second, the sequence and putative conformation of this site clearly resembles those typical of nucleotide-binding sites, making SAM binding its plausible function (Haydock et al, 1991;Wu et al, 1992).…”

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confidence: 99%

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Computer-assisted identification of a putative methyltransferase domain in NS5 protein of flaviviruses and 2 protein of reovirus

Koonin

1993

Journal of General Virology

214

150

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A sequence motif that is conserved in a number of Sadenosylmethionine (SAM)-utilizing methyltransferases and is implicated in SAM binding was identified in the N-terminal portion of NS5 proteins offlaviviruses and in 22 protein of reovirus. An additional conserved motif was shared by these viral proteins and two distinct groups of methyltransferases including as the prototypes Rhodobaeter capsulatus hydroxyneurosporene methylase (ertF gene product) and yeast 3,4-dihydroxy-5-hexaprenylbenzoate methylase (COQ3 gene product), respectively. Statistically significant similarity was revealed between the region of flavivirus NS5 containing the SAM-binding motif and a newly characterized family of putative methyltransferases from bacteria, yeast and plants, which is related to the Coq3 group. Amino acid sequence signatures were derived that are unique for NS5 proteins and different subsets of (putative) cellular methyltransferases. It is hypothesized that the Nterminal domain of NS5 is a methyltransferase involved in viral RNA capping. Thus NS5 may be a two-domain protein, with its C-terminal domain comprising the RNA-dependent RNA polymerase. The putative methyltransferase domain of flaviviruses is unrelated to the methyltransferase domain previously characterized in positive-strand RNA viruses of the alphavirus-like supergroup. The lack of sequence similarity and different location of the putative methyltransferase domain underscores the drastic difference in the genome layout offlaviviruses and alphaviruses. The identification of the putative methyltransferase domain in reovirus 22 protein is compatible with the available evidence that this protein is the viral capping enzyme.

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“…5; Refs. [5][6][7][8][9]. Yeast mutants in the COQ1, COQ2, COQ3, and COQ7 genes have been characterized (7,8,10,11).…”

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confidence: 99%

The COQ5 Gene Encodes a Yeast Mitochondrial Protein Necessary for Ubiquinone Biosynthesis and the Assembly of the Respiratory Chain

Dibrov¹,

Robinson²,

Lemire

1997

Journal of Biological Chemistry

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Saccharomyces cerevisiae is a facultative anaerobe capable of meeting its energy requirements by fermentation and is thus an ideal system for studying the biogenesis of respiring mitochondria. We have isolated a respiration-deficient mutant exhibiting a pleiotropic loss of the mitochondrial electron transport chain. The corresponding wild-type gene, COQ5, was cloned, sequenced, and able to restore respiratory growth. Deletion of the chromosomal COQ5 gene results in a respiration deficiency and reduced levels of respiratory protein components. Exogenously added decylubiquinone can partially restore electron transport chain function to mitochondrial membranes from the deletion mutant. The COQ5 nucleotide sequence predicts a polypeptide of 307 amino acids containing a mitochondrial targeting signal. COQ5p is 43% identical to the polypeptide predicted by the Escherichia coli open reading frame, o251 (1). The COQ5 gene, when introduced into E. coli, complements the respiratory deficiency of an ubiE mutant that maps near o251, suggesting that it is the yeast homolog of the ubiE gene product. We conclude that the COQ5 gene encodes the mitochondria-localized 2-hexaprenyl-6-methoxy-1,4-benzoquinone methyltransferase of the yeast ubiquinone biosynthetic pathway.

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Isolation and characterization of Escherichia coli mutants affected in aerobic respiration: the cloning and nucleotide sequence of ubiG: Identification of an S-adenosylmethionine-binding motif in protein, RNA, and small-molecule methyltransferases

Cited by 71 publications

References 51 publications

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

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

Computer-assisted identification of a putative methyltransferase domain in NS5 protein of flaviviruses and 2 protein of reovirus

The COQ5 Gene Encodes a Yeast Mitochondrial Protein Necessary for Ubiquinone Biosynthesis and the Assembly of the Respiratory Chain

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