title: The highly conserved KEOPS/EKC complex is essential for a universal tRNA modification, t6A.
abstract: The highly conserved Kinase, Endopeptidase and Other Proteins of small Size (KEOPS)/Endopeptidase-like and Kinase associated to transcribed Chromatin (EKC) protein complex has been implicated in transcription, telomere maintenance and chromosome segregation, but its exact function remains unknown. The complex consists of five proteins, Kinase-Associated Endopeptidase (Kae1), a highly conserved protein present in bacteria, archaea and eukaryotes, a kinase (Bud32) and three additional small polypeptides. We showed that the complex is required for a universal tRNA modification, threonyl carbamoyl adenosine (t6A), found in all tRNAs that pair with ANN codons in mRNA. We also showed that the bacterial ortholog of Kae1, YgjD, is required for t6A modification of Escherichia coli tRNAs. The ATPase activity of Kae1 and the kinase activity of Bud32 are required for the modification. The yeast protein Sua5 has been reported previously to be required for t6A synthesis. Using yeast extracts, we established an in vitro system for the synthesis of t6A that requires Sua5, Kae1, threonine, bicarbonate and ATP. It remains to be determined whether all reported defects of KEOPS/EKC mutants can be attributed to the lack of t6A, or whether the complex has multiple functions.
authors.affiliation: Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, USA.
authors.forename: Madhusudhan
authors.initials: M
authors.lastname: Srinivasan
authors.forename: Preeti
authors.initials: P
authors.lastname: Mehta
authors.forename: Yao
authors.initials: Y
authors.lastname: Yu
authors.forename: Evelyn
authors.initials: E
authors.lastname: Prugar
authors.forename: Eugene V
authors.initials: EV
authors.lastname: Koonin
authors.forename: A Wali
authors.initials: AW
authors.lastname: Karzai
authors.forename: Rolf
authors.initials: R
authors.lastname: Sternglanz
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives* / Q000378:metabolism; D000595:Amino Acid Sequence; D001483:Base Sequence; D008666:Metalloendopeptidases / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes; D009690:Nucleic Acid Conformation; D014176:Protein Biosynthesis; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D012343:RNA, Transfer / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: C509947:KEOPS complex, S cerevisiae; D046912:Multiprotein Complexes; D029701:Saccharomyces cerevisiae Proteins; C003268:N(6)-(N-threonylcarbonyl)adenosine; D012343:RNA, Transfer; C108301:BUD32 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; C480738:Kae1 protein, S cerevisiae; D008666:Metalloendopeptidases; D000241:Adenosine