IUBMB Enzyme Nomenclature


Accepted name: lysine/arginine leucyltransferase

Reaction: (1) L-leucyl-tRNALeu + N-terminal L-lysyl-[protein] = tRNALeu + N-terminal L-leucyl-L-lysyl-[protein]
(2) L-leucyl-tRNALeu + N-terminal L-arginyl-[protein] = tRNALeu + N-terminal L-leucyl-L-arginyl-[protein]

Other name(s): leucyl, phenylalanine-tRNA-protein transferase; leucyl-phenylalanine-transfer ribonucleate-protein aminoacyltransferase; leucyl-phenylalanine-transfer ribonucleate-protein transferase; L-leucyl-tRNA:protein leucyltransferase; leucyltransferase (misleading); L/FK,R-transferase; aat (gene name); L-leucyl-tRNALeu:protein leucyltransferase

Systematic name: L-leucyl-tRNALeu:[protein] N-terminal L-lysine/L-arginine leucyltransferase

Comments: Requires a univalent cation. The enzyme participates in the N-end rule protein degradation pathway in certain bacteria, by attaching the primary destabilizing residue L-leucine to the N-termini of proteins that have an N-terminal L-arginine or L-lysine residue. Once modified, the proteins are recognized by EC, the ClpAP/ClpS endopeptidase system. The enzyme also transfers L-phenylalanine in vitro, but this has not been observed in vivo [5]. cf. EC, aspartate/glutamate leucyltransferase, and EC, arginyltransferase.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 37257-22-0


1. Leibowitz, M.J. and Soffer, R.L. A soluble enzyme from Escherichia coli which catalyzes the transfer of leucine and phenylalanine from tRNA to acceptor proteins. Biochem. Biophys. Res. Commun. 36 (1969) 47-53. [PMID: 4894363]

2. Leibowitz, M.J. and Soffer, R.L. Enzymatic modification of proteins. 3. Purification and properties of a leucyl, phenylalanyl transfer ribonucleic acid protein transferase from Escherichia coli. J. Biol. Chem. 245 (1970) 2066-2073. [PMID: 4909560]

3. Soffer, R.L. Peptide acceptors in the leucine, phenylalanine transfer reaction. J. Biol. Chem. 248 (1973) 8424-8428. [PMID: 4587124]

4. Tobias, J.W., Shrader, T.E., Rocap, G. and Varshavsky, A. The N-end rule in bacteria. Science 254 (1991) 1374-1377. [PMID: 1962196]

5. Shrader, T.E., Tobias, J.W. and Varshavsky, A. The N-end rule in Escherichia coli: cloning and analysis of the leucyl, phenylalanyl-tRNA-protein transferase gene aat. J. Bacteriol. 175 (1993) 4364-4374. [PMID: 8331068]

6. Abramochkin, G. and Shrader, T.E. The leucyl/phenylalanyl-tRNA-protein transferase. Overexpression and characterization of substrate recognition, domain structure, and secondary structure. J. Biol. Chem. 270 (1995) 20621-20628. [PMID: 7657641]

[EC created 1972, modified 1976, modified 2013, modified 2016]

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