Structure and organization of Escherichia coli genes involved in biosynthesis of the deazaguanine derivative queuine, a nutrient factor for eukaryotes

Reuter, Klaus; Slany, Robert K.; Ullrich, Frank; Kersten, H.

doi:10.1128/jb.173.7.2256-2264.1991

Cited by 70 publications

(64 citation statements)

References 30 publications

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“…Homologues of the P. gingivalis W50 47 kDa immunodominant antigen (GenBank accession no. AF153770) and a tRNA guanine transglycosylase (Tgt ; Reuter et al, 1991) were located approximately 700 bp upstream and downstream of the pfs\luxS locus, respectively (Fig. 1a).…”

Section: Characterization Of a P Gingivalis Luxs Orthologuementioning

confidence: 99%

LuxS-dependent quorum sensing in Porphyromonas gingivalis modulates protease and haemagglutinin activities but is not essential for virulence

et al. 2002

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Porphyromonas gingivalis is a Gram-negative black-pigmented obligate anaerobe implicated in the aetiology of human periodontal disease. The virulence of P. gingivalis is associated with the elaboration of the cysteine proteases Arg-gingipain (Rgp) and Lys-gingipain (Kgp), which are produced at high bacterial cell densities. To determine whether quorum sensing plays a role in the regulation of Rgp and Kgp, biosensors capable of detecting either Nacylhomoserine lactone (AHLs) or the luxS-dependent autoinducer (AI-2) quorum-sensing signalling molecules in spent culture supernatants were first employed. While no AHLs could be detected, the Vibrio harveyi BB170 biosensor was activated by spent P. gingivalis W50 culture supernatants. The P. gingivalis luxS gene was cloned and demonstrated to restore AI-2 production in the Escherichia coli luxS mutant DH5α. Mutation of luxS abolished AI-2 production in P. gingivalis. Western blotting using antibodies raised against the recombinant protein revealed that LuxS levels increased throughout growth even though AI-2 activity was only maximally detected at the midexponential phase of growth and disappeared by the onset of stationary phase. Similar results were obtained with E. coli DH5α transformed with luxS, suggesting that AI-2 production is not limited by a lack of LuxS protein. Analysis of Rgp and Kgp protease activities revealed that the P. gingivalis luxS mutant produced around 45 % less Rgp and 30 % less Kgp activity than the parent strain. In addition, the luxS mutant exhibited a fourfold reduction in haemagglutinin titre. However, these reductions in virulence determinant levels were insufficient to attenuate the luxS mutant in a murine lesion model of P. gingivalis infection.

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Section: Characterization Of a P Gingivalis Luxs Orthologuementioning

confidence: 99%

LuxS-dependent quorum sensing in Porphyromonas gingivalis modulates protease and haemagglutinin activities but is not essential for virulence

et al. 2002

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Section: The Modified Base Queuine [Q; 7-5-( [(Ls4s5r)-45-di-mentioning

confidence: 99%

“…During the QueA reaction, epoxy-queuosine is formed that is finally reduced to queuosine (Q) by a vitamin-B ,,-dependent, unidentified enzyme [3]. The genes, tgt and queA, are localized on the Escherichia coli genome in one operon [4].Mammals obtain q from nutrients or the intestinal flora [5-91. Specific eukaryotic Tgt enzymes insert the q-factor in a practically irreversible reaction into the wobble position of cytosolic and of mitochondrial tRNA,,, species [5-71.…”

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The nutrient factor queuine protects HeLa cells from hypoxic stress and improves metabolic adaptation to oxygen availability

Reisser

Langgut

Kersten

1994

European Journal of Biochemistry

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Queuine (q), a cyclopentendiol derivative of 7-aminomethyl-7-deazaguanine, is a nutrient factor for lower and higher eukaryotes, except yeast; it is synthesized in eubacteria partly at the level of tRNA. In eukaryotes q is preferentially inserted into the wobble position of specific tRNAs in differentiated and adult tissues, but occurs mainly free in embryonic and fast proliferating cells. HeLa cells grow to a higher cell densitiy under aerobic than under hypoxic conditions only when supplemented with q. Here we show that in hypoxically grown HeLa cells, sufficiently supplied with q, free q accumulated when serum factors become limiting while the respective tRNAs remained completely q deficient. In these cells the levels of lactate dehydrogenase A (LDH A) mRNA and of LDH A protein were at least twofold higher than in aerobically grown cells, independent of the absence or presence of q. In response to q the LDH A, isoenzyme was further activated by a post-translational mechanism. In q-deficient HeLa cells the activity of the major anoxic stress protein, LDHk, increased as a result of hypoxia; this increase was suppressed by q. In aerobically grown, q-deficient cells significant activities of LDH A, and LDH, were present ; both activities were markedly lowered by q, while the mitochondrial electron flow was improved. The results show that free q is essential for relieving hypoxic stress in HeLa cells that results from oxygen limitation. The modified base queuine [q; 7-5-( [(lS,4S,5R)-4,5-di-anine], is synthesized in eubacteria only. During the biosynthesis GTP is converted to the precursor 7-aminomethyl-7-deazaguanine by so far unknown steps. The tRNA guanine transglycosylase (Tgt) exchanges this precursor specifically for the guanine residue in the anticodons GUN of tRNAs specifying the amino acids Asn, Asp, His and Tyr [l]. The cyclopentendiol moiety is derived from the ribose residue of S-adenosylmethionine and is attached to the modified tRNA precursor by a novel AdoMet-dependent reaction that is catalyzed by the tRNA ribosyltransferase-isomerase (QueA) [2]. During the QueA reaction, epoxy-queuosine is formed that is finally reduced to queuosine (Q) by a vitamin-B ,,-dependent, unidentified enzyme [3]. The genes, tgt and queA, are localized on the Escherichia coli genome in one operon [4].Mammals obtain q from nutrients or the intestinal flora [5-91. Specific eukaryotic Tgt enzymes insert the q-factor in a practically irreversible reaction into the wobble position of cytosolic and of mitochondrial tRNA,,, species [5-71.

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“…The preQ 1 base is subsequently transferred to the appropriate tRNA in a guanine-exchange reaction catalyzed by a tRNA-guanine transglycosylase (TGT) (15). It is then further modified in situ to give Q (16). A second 7-deazaguanosine tRNA modification, archaeosine, is found in all archaeal tRNAs at position 15 of the D-loop (17).…”

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Identification of Four Genes Necessary for Biosynthesis of the Modified Nucleoside Queuosine

Reader

Metzgar

Schimmel

et al. 2004

Journal of Biological Chemistry

138

134

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Queuosine (Q) is a hypermodified 7-deazaguanosine nucleoside located in the anticodon wobble position of four amino acid-specific tRNAs. In bacteria, Q is produced de novo from GTP via the 7-deazaguanosine precursor preQ 1 (7-aminoethyl 7-deazaguanine) by an uncharacterized pathway. PreQ 1 is subsequently transferred to its specific tRNA by a tRNA-guanine transglycosylase (TGT) and then further modified in situ to produce Q. Here we use comparative genomics to implicate four gene families (best exemplified by the B. subtilis operon ykvJKLM) as candidates in the preQ 1 biosynthetic pathway. Deletions were constructed in genes for each of the four orthologs in Acinetobacter. High pressure liquid chromatography analysis showed the Q nucleoside was absent from the tRNAs of each of four deletion strains. Electrospray ionization mass spectrometry confirmed the absence of Q in each mutant strain. Finally, introduction of the Bacillus subtilis ykvJKLM operon in trans complemented the Q deficiency of the two deletion mutants that were tested. Thus, the products of these four genes (named queC, -D, -E, and -F) are essential for the Q biosynthetic pathway.Nucleoside modification typically occurs in ϳ10% of the nucleosides of a particular tRNA but can involve as many as 25% of the nucleosides for a specific tRNA (1). Over 80 modified nucleosides have been characterized (1), many of which are phylogenetically conserved. The nature of nucleoside modification varies from simple methylation of the base or ribose ring to extensive "hypermodification" of the canonical bases. The latter involves multiple enzymatic steps and can result in substantive structural changes (2). Queuosine (Q) 1 is an example of a highly modified nucleoside located in the anticodon wobble position 34 of tRNAs specific for Tyr, His, Asp, and Asn (3). With few exceptions (such as yeast and mycoplasma), it is widely distributed in most prokaryotic and eukaryotic phyla (4). Q is based on a very unusual 7-deazaguanosine core, which is further modified by addition of a cyclopentendiol ring (5, 6). The Q modification has long been known and has been implicated in a number of disparate physiological phenomena, such as eukaryotic cell proliferation and differentiation (7-10), tyrosine biosynthesis (11), and bacterial virulence (12). However, despite the presence of Q in the tRNA anticodon loop, no definitive role for Q in translation has been established (13).Unlike eukaryotes that import the queuine base, bacteria synthesize Q modification de novo from a GTP starting block (14). The first stage of synthesis gives 7-cyano-7-deazaguanosine (preQ 0 ) that is then further modified into 7-aminoethyl 7-deazaguanine (preQ 1 ) (Fig. 1). The preQ 1 base is subsequently transferred to the appropriate tRNA in a guanine-exchange reaction catalyzed by a tRNA-guanine transglycosylase (TGT) (15). It is then further modified in situ to give Q (16). A second 7-deazaguanosine tRNA modification, archaeosine, is found in all archaeal tRNAs at position 15 of the D-loop (17). Archa...

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Structure and organization of Escherichia coli genes involved in biosynthesis of the deazaguanine derivative queuine, a nutrient factor for eukaryotes

Cited by 70 publications

References 30 publications

LuxS-dependent quorum sensing in Porphyromonas gingivalis modulates protease and haemagglutinin activities but is not essential for virulence

LuxS-dependent quorum sensing in Porphyromonas gingivalis modulates protease and haemagglutinin activities but is not essential for virulence

The nutrient factor queuine protects HeLa cells from hypoxic stress and improves metabolic adaptation to oxygen availability

Identification of Four Genes Necessary for Biosynthesis of the Modified Nucleoside Queuosine

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