The tertiary structure of salt-extracted ribosomal proteins from Escherichia coli as studied by proton magnetic resonance spectroscopy and limited proteolysis experiments.
Ribosomal proteins from Escherichia coli have been isolated by a mild purification procedure. Their tertiary structure has been explored by two techniques, proton magnetic resonance and limited proteolysis. A number of proteins when subjected to limited proteolysis produce resistant fragments in good yields. In most cases this does not depend on the specificity of the enzyme used. The proteins S15, S16, S17 and L30 are not degraded at all, whereas a few proteins are very susceptible to proteolysis. 1H-NMR experiments show that the majority of the ribosomal proteins have a uniquely folded tertiary structure. This is particularly pronounced in the four proteins mentioned above which resist proteolysis. In general, a good agreement is observed between the degree of proteolytic resistance and the amount of folding indicated by NMR spectroscopy. Similar studies on a few ribosomal proteins purified under denaturing conditions show that, in contrast, these protein preparations are not structurally homogeneous and that they contain a mixture of denatured and renatured molecules. The results are interpreted in terms of a compactly folded tertiary structure for the four proteinase-resistant proteins while the majority of the other proteins appear to have two domains, one compactly folded and resistant to proteinase and the other flexible and susceptible to proteolysis. A few proteins seem to have a completely flexible structure and can therefore be easily degraded.
Littlechild
J
J
Malcolm
A
A
Paterakis
K
K
Ackermann
I
I
Dijk
J
J
D001426:Bacterial Proteins / Q000302:isolation & purification; D004926:Escherichia coli / Q000032:analysis*; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy; D010447:Peptide Hydrolases / Q000378:metabolism; D010455:Peptides / Q000302:isolation & purification; D011487:Protein Conformation; D012269:Ribosomal Proteins / Q000302:isolation & purification
D001426:Bacterial Proteins; D010455:Peptides; D012269:Ribosomal Proteins; D010447:Peptide Hydrolases