The Primary Structure of an Acidic Protein from 50‐S Ribosomes of Escherichia coli which is Involved in GTP Hydrolysis Dependent on Elongation Factors G and T

Abstract

The primary structures of the ribosomal proteins A, (= L,) and A, (= L,,) have been elucidated. Comparison of the two amino acid sequences confirms earlier studies by us (1972) which indicated that the two proteins are identical except that A, possesses an N-terminal acetyl group.Sequencing of tryptic and chymotryptic peptides was accomplished primarily by automatic solid-phase Edman degradation of 50-to 70-nanomole peptide samples. A large tryptic peptide T,Phe, which could not be sequenced by this method, was fragmented with elastase and its sequence mainly derived by conventional methods. The sequence of the first 51 residues of the nonacetylated A,-protein was obtained by Edman degradation in the Beckman sequencer.A-protein comprises three distinct regions : I (residues 1 -55), which is negatively-charged and hydrophobic, I1 (56-81), which is positively charged, and I11 (82-120), which is negatively charged and hydrophilic. &-Helix promoting residues are located primarily in regions I and 111. e-N-Monomethyllysine, which occurs in 50°/, of the A, and A, chains is located in the more flexible region I1 at position 81.The distinctive clustering of hydrophobic and charged residues is quite remarkable and suggests that in situ certain of these regions may contain a binding site for components involved in peptide chain elongation.

Primary structures of mutationally altered ribosomal protein L7/L12 and their effects on cellular growth and translational accuracy

“…After completion of tryptic digestion [38] the solution was brought to pH 4.3 [35]. The TIMet peptide (positions 5-29) was purified from the precipitate [35].…”

“…The resulting peptides were separated on a Sephadex G-50 superfine column in the presence of 50 mM NaHC03, 0.1% sodium dodecylsulfate pH 9.0. The large peptide, which starts with a Glu at position 27 [35], was used for sequencing from position 27 to position 76. Sodium dodecylsulfate was removed according to Amons and Schrier [36].…”

“…The amino acid phenylthiohydantoins were identified by reversed-phase, high-performance liquid chromatography [41]. The peptide nomenclature is described elsewhere [35].…”

Acidic Phosphoproteins of the 60‐S Ribosomal Subunits from HeLa Cells

“…Two acidic proteins of Escherichia coli ribosomes, L7 and L12, differ only in their N-terminal serine residue, which is acetylated in L7 [1,2]. These two proteins are engaged in several steps of peptide synthesis (for review, see [3]).…”

A comparison of the amino‐terminal sequence of the L7/L12‐type proteins of Artemia salina and Saccharomyces cerevisiae

“…Up to now, only the complete primary structure of Escherichia coli L7/L12 protein has been published [3]. Visentin et al [4] performed sequence studies of the amino-terminal region of the Bacillus stearothermophilus protein, and they found that the first 15 residues are highly homologous with residues 2-16 of the E. coli protein.…”