Abstract of the PDB Structure's related Publication:
The yeast KEOPS protein complex comprising Kae1, Bud32, Cgi121, Pcc1 and Gon7 is responsible for the essential tRNA threonylcarbamoyladenosine (t(6)A) modification. Deletion of genes coding for the KEOPS subunits also affects telomere elongation and transcriptional regulation. In the present work, the crystal structure of Bud32/Cgi121 in complex with ADP revealed that ADP is bound in the catalytic site of Bud32 in a canonical manner characteristic of Protein Kinase A (PKA) family proteins. We found that Gon7 forms a stable heterodimer with Pcc1 and report the crystal structure of the Pcc1-Gon7 heterodimer. Gon7 interacts with the same Pcc1 region engaged in the archaeal Pcc1 homodimer. We further show that yeast KEOPS, unlike its archaeal counterpart, exists as a heteropentamer in which Gon7, Pcc1, Kae1, Bud32 and Cgi121 also adopt a linear arrangement. We constructed a model of yeast KEOPS that provides structural insight into the role of Gon7. The model also revealed the presence of a highly positively charged crater surrounding the entrance of Kae1 that likely binds tRNA.
Member of the protein kinase superfamily Bud32 is conserved in all eukaryotic and archaeal organisms. It is absent in bacteria. Bud32 forms part of the KEOPS (kinase Endopeptidase and other proteins of small size) complex together with other subunits. KEOPS works generating t6A, an essential post-transcriptional modification, that is is present in tRNAs. This modification is present in position A37 and binds to ANN codons. This modification ensures translation fidelity. It is a RIO-type kinase (PRPK), a p53-related protein kinase in human. At variance with most archaeal Bud32, the S. cerevisiae Bud32 is not fused to SceKae1
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