Probing ribosome function and the location of Escherichia coli ribosomal protein L5 with a monoclonal antibody.
A monoclonal antibody specific for Escherichia coli ribosomal protein L5 was isolated from a cell line obtained from Dr. David Schlessinger. Its unique specificity for L5 was confirmed by one- and two-dimensional electrophoresis and immunoblotting. The antibody recognized L5 both in 50 S subunits and 70 S ribosomes. Both antibody and Fab fragments had similar effects on the ribosome functions tested. Antibody bound to 50 S subunits inhibited their reassociation with 30 S subunits at 10 mM Mg2+ but not 15 mM, the concentration present for in vitro protein synthesis. The 70 S couples were not dissociated by the antibody. The antibody caused inhibition of polyphenylalanine synthesis at molar ratios to 50 S or 70 S particles of 4:1. The major inhibitory effect was on the peptidyltransferase reaction. There was no effect on either elongation factor binding or the associated GTPase activities. The site of antibody binding to 50 S was determined by electron microscopy. Antibody was seen to bind beside the central protuberance or head of the particle, on the side away from the L7/L12 stalk, and on or near the region at which the 50 S subunit interacts with the 30 S subunit. This site of antibody binding is fully consistent with its biochemical effects.
Nag
B
B
Tewari
D S
DS
Sommer
A
A
Olson
H M
HM
Glitz
D G
DG
Traut
R R
RR
D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D002460:Cell Line; D004926:Escherichia coli / Q000378:metabolism* / Q000648:ultrastructure; D007700:Kinetics; D012269:Ribosomal Proteins / Q000276:immunology / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism* / Q000648:ultrastructure
D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D012269:Ribosomal Proteins; C029742:ribosomal protein L5