Formation of thiolated nucleosides present in tRNA from Salmonella enterica serovar Typhimurium occurs in two principally distinct pathways.
2004 (English)In: Journal of Bacteriology, ISSN 0021-9193, E-ISSN 1098-5530, Vol. 186, no 3, 758-766 p.Article in journal (Refereed) Published
tRNA from Salmonella enterica serovar Typhimurium contains five thiolated nucleosides, 2-thiocytidine (s(2)C), 4-thiouridine (s(4)U), 5-methylaminomethyl-2-thiouridine (mnm(5)s(2)U), 5-carboxymethylaminomethyl-2-thiouridine (cmnm(5)s(2)U), and N-6-(4-hydroxyisopentenyl)-2-methylthioadenosine (ms(2)io(6)A). The levels of all of them are significantly reduced in cells with a mutated iscS gene, which encodes the cysteine desulfurase IscS, a member of the ISC machinery that is responsible for [Fe-S] cluster formation in proteins. A mutant (iscU52) was isolated that carried an amino acid substitution (S107T) in the IscU protein, which functions as a major scaffold in the formation of [Fe-S] clusters. In contrast to the iscS mutant, the iscU52 mutant showed reduced levels of only two of the thiolated nucleosides, ms(2)io(6)A (10-fold) and s(2)C (more than 2-fold). Deletions of the iscU, hscA, or fdx genes from the isc operon lead to a similar tRNA thiolation pattern to that seen for the iscU52 mutant. Unexpectedly, deletion of the iscA gene, coding for an alternative scaffold protein for the [Fe-S] clusters, showed a novel tRNA thiolation pattern, where the synthesis of only one thiolated nucleoside, ms(2)io(6)A, was decreased twofold. Based on our results, we suggest two principal distinct routes for thiolation of tRNA: (i) a direct sulfur transfer from IscS to the tRNA modifying enzymes ThiI and MnmA, which form s(4)U and the s(2)U moiety of (c)mnm(5)s(2)U, respectively; and (ii) an involvement of [Fe-S] proteins (an unidentified enzyme in the synthesis of s(2)C and MiaB in the synthesis of ms(2)io(6)A) in the transfer of sulfur to the tRNA.
Place, publisher, year, edition, pages
2004. Vol. 186, no 3, 758-766 p.
Escherichia coli Proteins, HSP70 Heat-Shock Proteins/physiology, Iron-Sulfur Proteins/metabolism, Mutation, Nucleosides/*metabolism, Operon, RNA; Bacterial/*metabolism, RNA; Transfer/*metabolism, Salmonella typhimurium/*genetics/growth & development, Sulfhydryl Compounds/*metabolism, Thiouridine/metabolism
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:umu:diva-16737DOI: 10.1128/JB.186.3.758-766.2004PubMedID: 14729702OAI: oai:DiVA.org:umu-16737DiVA: diva2:156410