Diversity of archaeosine synthesis in crenarchaeota.
Archaeosine (G(+)) is found at position 15 of many archaeal tRNAs. In Euryarchaeota, the G(+) precursor, 7-cyano-7-deazaguanine (preQ(0)), is inserted into tRNA by tRNA-guanine transglycosylase (arcTGT) before conversion into G(+) by ARChaeosine Synthase (ArcS). However, many Crenarchaeota known to harbor G(+) lack ArcS homologues. Using comparative genomics approaches, two families that could functionally replace ArcS in these organisms were identified: (1) GAT-QueC, a two-domain family with an N-terminal glutamine amidotransferase class-II domain fused to a domain homologous to QueC, the enzyme that produces preQ(0) and (2) QueF-like, a family homologous to the bacterial enzyme catalyzing the reduction of preQ(0) to 7-aminomethyl-7-deazaguanine. Here we show that these two protein families are able to catalyze the formation of G(+) in a heterologous system. Structure and sequence comparisons of crenarchaeal and euryarchaeal arcTGTs suggest the crenarchaeal enzymes have broader substrate specificity. These results led to a new model for the synthesis and salvage of G(+) in Crenarchaeota.
Gabriela
G
Phillips
Manal A
MA
Swairjo
Kirk W
KW
Gaston
Marc
M
Bailly
Patrick A
PA
Limbach
Dirk
D
Iwata-Reuyl
Valérie
V
de Crécy-Lagard
D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019615:Crenarchaeota / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D023281:Genomics; D006151:Guanosine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D016415:Sequence Alignment; D013379:Substrate Specificity
D019843:Archaeal Proteins; D006151:Guanosine; C081066:archaeosine