Project Details
Projekt
Aminocarboxypropyl (acp) modified nucleotides in RNA: enzymes, structures and functions
Subject Area
Biochemistry
Structural Biology
Structural Biology
Term
from 2018 to 2022
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 404989355
The m1acp3Ѱ1191 (S. cerevisiae) hypermodification is unique and presumably present in the 18S rRNAs of all eukaryotes. During the first period of the SPP we functionally and structurally characterized Tsr3 - the enzyme transferring an acp group to m1Ѱ during the last step in the biosynthesis of this hypermodified nucleotide. We solved X-ray structures of archaeal homologs of Tsr3 in the SAM-bound and the apo state. Surprisingly, Tsr3 showed the same fold similar as SPOUT-class RNA methyltransferases but a unique SAM-binding mode that supports the transfer of the acp group of SAM to its RNA substrate. A DTW sequence motive is an integral structural part of this SAM-binding site. These structural insights and sequence similarities opened a new access for the identification of acp transferases. Proteins with predicted DTW motives are widespread in all domains of life. For E. coli our current data suggest that the DTW protein YfiP catalyzes the acp3U-47 modification in tRNAs but is only efficient when an m7G-46 modification is also present. Furthermore, in higher eukaryotes several homologs of tRNA acp transferases are present, some of which possibly modify specifically tRNAs from different organelles. The functional importance of acp modification for tRNAs will be investigated. We also will delineate the structural basis for tRNA recognition of this enzyme class and compare it with the probably different binding mode of Tsr3 proteins to their ribosomal RNA substrates.
DFG Programme
Priority Programmes
