Photoaffinity labeling of the pactamycin binding site on eubacterial ribosomes

Journal Article · Tue Jul 02 00:00:00 EDT 1985 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00335a040· OSTI ID:6171223

Tejedor, F; Amils, R; Ballesta, J P

Pactamycin, an inhibitor of the initial steps of protein synthesis, has an acetophenone group in its chemical structure that makes the drug a potentially photoreactive molecule. In addition, the presence of a phenolic residue makes it easily susceptible to radioactive labeling. Through iodination, one radioactive derivative of pactamycin has been obtained with biological activities similar to the unmodified drug when tested on in vivo and cell-free systems. With the use of (/sup 125/I)iodopactamycin, ribosomes of Escherichia coli have been photolabeled under conditions that preserve the activity of the particles and guarantee the specificity of the binding sites. Under these conditions, RNA is preferentially labeled when free, small ribosomal subunits are photolabeled, but proteins are the main target in the whole ribosome. This indicates that an important conformational change takes place in the binding site on association of the two subunits. The major labeled proteins are S2, S4, S18, S21, and L13. These proteins in the pactamycin binding site are probably related to the initiation step of protein synthesis.

• Research Organization: Centro de Biologia Molecular, Madrid, Spain
• OSTI ID: 6171223
• Journal Information: Biochemistry; (United States), Vol. 14
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
ANTIBIOTICS
RECEPTORS
PROTEINS
LABELLING
AFFINITY
BIOCHEMICAL REACTION KINETICS
ESCHERICHIA COLI
IODINATION
RIBOSOMES
RNA
ANTI-INFECTIVE AGENTS
BACTERIA
CELL CONSTITUENTS
CHEMICAL REACTIONS
DRUGS
HALOGENATION
KINETICS
MICROORGANISMS
NUCLEIC ACIDS
ORGANIC COMPOUNDS
ORGANOIDS
REACTION KINETICS
550201* - Biochemistry- Tracer Techniques