title: Placement of the alpha-sarcin loop within the 50S subunit: evidence derived using a photolabile oligodeoxynucleotide probe.
abstract: We report the synthesis of a radioactive, photolabile oligodeoxyribonucleotide probe and its exploitation in identifying 50S ribosomal subunit components neighboring the alpha-sarcin loop. The probe is complementary to 23S rRNA nt 2653-2674. Photolysis of the complex formed between the probe and 50S subunits leads to site-specific probe photoincorporation into proteins L2, the most highly labeled protein, L1, L15, L16 and L27, labeled to intermediate extents, and L5, L9, L17 and L24, each labeled to a minor extent. Portions of each of these proteins thus lie within 23 A of nt U2653. These results lead us to conclude that the alpha-sarcin loop is located at the base of the L1 projection within the 50S subunit. Such placement, near the peptidyl transferase center, provides a rationale for the extreme sensitivity of ribosomal function to cleavage of the alpha-sarcin loop.
authors.affiliation: Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA.
authors.forename: P
authors.initials: P
authors.lastname: Muralikrishna
authors.forename: R W
authors.initials: RW
authors.lastname: Alexander
authors.forename: B S
authors.initials: BS
authors.lastname: Cooperman
mesh_terms: D000345:Affinity Labels; D001386:Azides / Q000378:metabolism; D001665:Binding Sites; D018076:DNA, Complementary / Q000378:metabolism; D004722:Endoribonucleases / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins; D005816:Genetic Complementation Test; D007553:Isotope Labeling; D009690:Nucleic Acid Conformation; D015345:Oligonucleotide Probes / Q000378:metabolism*; D010761:Phosphorus Radioisotopes; D012335:RNA, Ribosomal / Q000378:metabolism*; D012338:RNA, Ribosomal, 23S / Q000235:genetics / Q000378:metabolism*
chemical_list: D000345:Affinity Labels; D001386:Azides; D018076:DNA, Complementary; D005656:Fungal Proteins; D015345:Oligonucleotide Probes; D010761:Phosphorus Radioisotopes; D012335:RNA, Ribosomal; D012338:RNA, Ribosomal, 23S; C014801:alpha-sarcin; C029534:hydroxysuccinimidyl-4-azidobenzoate; D004722:Endoribonucleases