The subunit interface of the Escherichia coli ribosome: Identification of proteins at the interface between the 30 S and 50 S subunits by crosslinking with 2-iminothiolane☆

摘要: Abstract The 70 S ribosomes of Escherichia coli were treated with 2-iminothiolane the resultant addition 110 sulfhydryl groups per ribosome. modified oxidized to promote disulfide bond formation, some which formed intermolecular crosslinks. About 50% crosslinked did not dissociate when exposed low concentrations magnesium in absence reducting agent. Dissociation took place presence reducing agents, indicated that subunits had become covalently linked by linkages. Proteins extracted from purified first fractionated polyacrylamide/urea gel electrophoresis. proteins sequential slices these gels analyzed two-dimensional polyacrylamide/sodium dodecyl sulfate diagonal Monomeric derived dimers appeared below containing non-crosslinked proteins, since second electrophoresis, but first, is run under conditions cleave species. Final identification each dimer was made radioiodination followed electrophoresis non-radioactive total as markers. This paper describes 23 protein contained one two different ribosomal subunits. implicated must have part their structure proximity other subunit and are therefore defined “interface proteins”. group interface thus includes 50 5 RNA: complex 30 at initiation site. Correlations between functional data discussed.