Two-dimensional crystalline sheets of Bacillus stearothermophilus 50S ribosomal subunits containing a nascent polypeptide chain

Polylysine chains were synthesized on Bacillus stearothermophilus ribosomes in a poly(A)-programmed in vitro system. After separation of the ribosomal subunits by sucrose gradient centrifugation, the polylysine chains (in contrast to the polyphenylalanine chains synthesized in a poly(U) system) reproducibly remained attached to the large ribosomal subunit. It was possible to produce two-dimensional crystalline sheets from the large ribosomal subunits containing the polylysine chains. These sheets are an essential prerequisite for three-dimensional reconstruction studies aiming to show that the tunnel in the large ribosomal subunit provides a path for the nascent polypeptide chain.