Identification by site-directed mutagenesis of amino acid residues in ribosomal protein L2 that are essential for binding to 23S ribosomal RNA

Nao Harada, Kouta Maemura, Nobuyuki Yamasaki, Makoto Kimura

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11 Citations (Scopus)

Abstract

The ribosomal protein L2 (BstL2) from Bacillus stearothermophilus is a primary 23S rRNA binding protein. We made use of site-directed mutagenesis to identify essential basic and aromatic amino acid residues for 23S rRNA binding. Four mutants, R68Q, K70Q, R86Q, and R155Q, in which Arg-68, Lys-70, Arg-86, and Arg-155, respectively, are replaced by the Gln residue, showed reduced binding affinities as compared with that of the wild type BstL2 (a binding constant K=8.93 μM-1): K values of these mutants range between 0.24 and 1.86 μM-1. As for aromatic amino acids, replacements of Phe-66, Tyr-95 or Tyr-102 by alanine significantly abolished the binding affinities. CD analysis of the mutant proteins indicated that the mutations of four basic residues (Arg-68, Lys-70, Arg-86 and Arg-155) did not affect protein structure, whereas those of aromatic residues (Phe-66, Tyr-95, and Tyr-102) appeared to cause slight structural perturbations. These results, together with sequence comparison of L2 family proteins, suggest that Arg-86 and Arg-155 in BstL2 may act as positively charged recognition groups for negatively charged phosphate backbone of the 23S rRNA, and that Phe-66, Tyr-95, and Tyr-102 may be candidate residues which stabilize the BstL2-23S rRNA interaction through intramolecular interactions. Copyright (C) 1998 Elsevier Science B.V.

Original languageEnglish
Pages (from-to)176-186
Number of pages11
JournalBiochimica et Biophysica Acta - Protein Structure and Molecular Enzymology
Volume1429
Issue number1
DOIs
Publication statusPublished - Dec 8 1998

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology

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