Abstract of the PDB Structure's related Publication:
The EKC/KEOPS yeast complex is involved in telomere maintenance and transcription. The Bud32p and kinase-associated endopeptidase 1 (Kaelp) components of the complex are totally conserved in eukarya and archaea. Their genes are fused in several archaeal genomes, suggesting that they physically interact. We report here the structure of the Methanocaldococcus jannaschii Kae1/Bud32 fusion protein MJ1130. Kae1 is an iron protein with an ASKHA fold and Bud32 is an atypical small RIO-type kinase. The structure MJ1130 suggests that association with Kae1 maintains the Bud32 kinase in an inactive state. We indeed show that yeast Kae1p represses the kinase activity of yeast Bud32p. Extensive conserved interactions between MjKae1 and MjBud32 suggest that Kae1p and Bud32p directly interact in both yeast and archaea. Mutations that disrupt the Kae1p/Bud32p interaction in the context of the yeast complex have dramatic effects in vivo and in vitro, similar to those observed with deletion mutations of the respective components. Direct interaction between Kae1p and Bud32p in yeast is required both for the transcription and the telomere homeostasis function of EKC/KEOPS.
Archaeal Kae1 (Kinase-Associated Endopeptidase 1) is the ortholog eukaryal Kae1/bacterial TsaD (YgjD) and the paralog of mitochondrial Qri7. In M. jannaschi, as in most archaea, it is fused to Bud32 kinase. This iron metalloprotein Kae1, together with other proteins of the so-called EKC/KEOPS complex (Bud32, Pcc1 and Cgi121), ATP, threonine and bicarbonate as cofactors, they catalyze the in vivo formation of t6A (threonyl-carbamoylation, probably a processive type of reaction) at position 37 of all eukaryotic tRNA decoding ANN codons (ile, Met, Thr, Lys, Asn, Arg and Ser). However the detailed stepwise mechanism of t6A formation is still not known (March 2012).
The universal Kae1 protein and the associated Bud32 kinase (PRPK), a mysterious protein couple probably essential for genome maintenance in Archaea and Eukarya.
Hecker A, Graille M, Madec E, Gadelle D, Le Cam E, van Tilbergh H, Forterre P
Atomic structure of the KEOPS complex: an ancient protein kinase-containing molecular machine.
Mao DY, Neculai D, Downey M, Orlicky S, Haffani YZ, Ceccarelli DF, Ho JS, Szilard RK, Zhang W, Ho CS, Wan L, Fares C, Rumpel S, Kurinov I, Arrowsmith CH, Durocher D, Sicheri F