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Crystal structures of leucyl/phenylalanyl‐tRNA‐protein transferase and its complex with an aminoacyl‐tRNA analog
Author(s) -
Suto Kyoko,
Shimizu Yoshihiro,
Watanabe Kazunori,
Ueda Takuya,
Fukai Shuya,
Nureki Osamu,
Tomita Kozo
Publication year - 2006
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7601433
Subject(s) - transfer rna , biology , aminoacyl trna synthetase , transferase , aminoacyl trna , biochemistry , computational biology , enzyme , rna , gene
Eubacterial leucyl/phenylalanyl‐tRNA protein transferase (L/F‐transferase), encoded by the aat gene, conjugates leucine or phenylalanine to the N‐terminal Arg or Lys residue of proteins, using Leu‐tRNA Leu or Phe‐tRNA Phe as a substrate. The resulting N‐terminal Leu or Phe acts as a degradation signal for the ClpS‐ClpAP‐mediated N‐end rule protein degradation pathway. Here, we present the crystal structures of Escherichia coli L/F‐transferase and its complex with an aminoacyl‐tRNA analog, puromycin. The C‐terminal domain of L/F‐transferase consists of the GCN5‐related N‐acetyltransferase fold, commonly observed in the acetyltransferase superfamily. The p ‐methoxybenzyl group of puromycin, corresponding to the side chain of Leu or Phe of Leu‐tRNA Leu or Phe‐tRNA Phe , is accommodated in a highly hydrophobic pocket, with a shape and size suitable for hydrophobic amino‐acid residues lacking a branched β‐carbon, such as leucine and phenylalanine. Structure‐based mutagenesis of L/F‐transferase revealed its substrate specificity. Furthermore, we present a model of the L/F‐transferase complex with tRNA and substrate proteins bearing an N‐terminal Arg or Lys.