Crosslinking of elongation factor Tu to tRNAPheby trans‐diamminedichloroplatinum (II) Characterization of two crosslinking sites on EF‐Tu

In a preceding paper [(1987) Nucleic Acids Res. 15, 5787–5801], we have used trans‐diamminedichloroplatinum (II) to induce reversible RNA‐protein crosslinks within the ternary EF‐Tu/GTP/Phe‐tRNAPhecomplex and have identified two crosslinking sites on the tRNA. The aim of the present paper is to determine the crosslinking sites on EF‐Tu. Two tryptic peptides located in domain I could be identified, a major one (residues 45–74) and a minor one (residues 117–154). The use of Staphylococcus aureusV8 protease led to the isolation of two major peptides (residues 56–68 and 64–68) and one minor peptide (118–124). These results are discussed in the light of the current knowledge of the topography of the EF‐Tu/tRNA complex.