The iscS gene is essential for the biosynthesis of 2-selenouridine in tRNA and the selenocysteine-containing formate dehydrogenase H

AUTOR(ES)

Mihara, Hisaaki

FONTE

The National Academy of Sciences

RESUMO

Three NifS-like proteins, IscS, CSD, and CsdB, from Escherichia coli catalyze the removal of sulfur and selenium from l-cysteine and l-selenocysteine, respectively, to form l-alanine. These enzymes are proposed to function as sulfur-delivery proteins for iron-sulfur cluster, thiamin, 4-thiouridine, biotin, and molybdopterin. Recently, it was reported that selenium mobilized from free selenocysteine is incorporated specifically into a selenoprotein and tRNA in vivo, supporting the involvement of the NifS-like proteins in selenium metabolism. We here report evidence that a strain lacking IscS is incapable of synthesizing 5-methylaminomethyl-2-selenouridine and its precursor 5-methylaminomethyl-2-thiouridine (mnm5s2U) in tRNA, suggesting that the sulfur atom released from l-cysteine by the action of IscS is incorporated into mnm5s2U. In contrast, neither CSD nor CsdB was essential for production of mnm5s2U and 5-methylaminomethyl-2-selenouridine. The lack of IscS also caused a significant loss of the selenium-containing polypeptide of formate dehydrogenase H. Together, these results suggest a dual function of IscS in sulfur and selenium metabolism.

Documentos Relacionados

• Nucleotide sequence and expression of the selenocysteine-containing polypeptide of formate dehydrogenase (formate-hydrogen-lyase-linked) from Escherichia coli.
• The Cysteine Desulfurase IscS Is Required for Synthesis of All Five Thiolated Nucleosides Present in tRNA from Salmonella enterica Serovar Typhimurium
• Selenium Is Mobilized In Vivo from Free Selenocysteine and Is Incorporated Specifically into Formate Dehydrogenase H and tRNA Nucleosides
• Selenocysteine-Containing Proteins in Anaerobic Benzoate Metabolism of Desulfococcus multivorans
• Requirement for IscS in Biosynthesis of All Thionucleosides in Escherichia coli