title: The Escherichia coli COG1738 Member YhhQ Is Involved in 7-Cyanodeazaguanine (preQ₀) Transport.
abstract: Queuosine (Q) is a complex modification of the wobble base in tRNAs with GUN anticodons. The full Q biosynthesis pathway has been elucidated inEscherichia coli. FolE, QueD, QueE and QueC are involved in the conversion of guanosine triphosphate (GTP) to 7-cyano-7-deazaguanine (preQ₀), an intermediate of increasing interest for its central role in tRNA and DNA modification and secondary metabolism. QueF then reduces preQ₀ to 7-aminomethyl-7-deazaguanine (preQ₁). PreQ₁ is inserted into tRNAs by tRNA guanine(34)transglycosylase (TGT). The inserted base preQ₁ is finally matured to Q by two additional steps involving QueA and QueG or QueH. Most Eubacteria harbor the full set of Q synthesis genes and are predicted to synthesize Q de novo. However, some bacteria only encode enzymes involved in the second half of the pathway downstream of preQ₀ synthesis, including the signature enzyme TGT. Different patterns of distribution of thequeF,tgt,queAandqueGorqueHgenes are observed, suggesting preQ₀, preQ₁ or even the queuine base being salvaged in specific organisms. Such salvage pathways require the existence of specific 7-deazapurine transporters that have yet to be identified. The COG1738 family was identified as a candidate for a missing preQ₀/preQ₁ transporter in prokaryotes, by comparative genomics analyses. The existence of Q precursor salvage was confirmed for the first time in bacteria, in vivo, through an indirect assay. The involvement of the COG1738 in salvage of a Q precursor was experimentally validated inEscherichia coli, where it was shown that the COG1738 family member YhhQ is essential for preQ₀ transport.
authors.affiliation: Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA. remizallot@ufl.edu.
authors.forename: Rémi
authors.initials: R
authors.lastname: Zallot
authors.affiliation: Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA. yuanyifeng@ufl.edu.
authors.forename: Yifeng
authors.initials: Y
authors.lastname: Yuan
authors.affiliation: Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA. vcrecy@ufl.edu.
authors.forename: Valérie
authors.initials: V
authors.lastname: de Crécy-Lagard
mesh_terms: D001692:Biological Transport; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006147:Guanine / Q000031:analogs & derivatives* / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009704:Nucleoside Q / Q000096:biosynthesis / Q000737:chemistry; D012349:RNA, Transfer, Asp
chemical_list: C000624711:7-cyano-7-deazaguanine; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D012349:RNA, Transfer, Asp; C000624712:YhhQ protein, E coli; D009704:Nucleoside Q; D006147:Guanine; C066856:7-deazaguanine
keywords: 7-deazapurine; COG1738; ECF-type ATP-binding cassette; preQ0; preQ1; queuine; queuosine; salvage; tRNA modification; transport