EFFECTS OF AMINO-ACID SUBSTITUTION ON THE THERMAL-STABILITY OF MS2 CAPSIDS LACKING GENOMIC RNA

The thermal stability of capsids of the bacteriophage MS2, lacking gen omic RNA, has been investigated using electron microscopy. Coat protei n mutants with amino acid substitutions at residues involved in making contacts at both inter-molecular interfaces and within the coat prote in subunit are also capable of forming 'empty' capsids of the same siz e and symmetry as the wild-type protein. Mutations have been character ised which are neutral, deleterious or advantageous in terms of therma l stability. In some cases, the results can be rationalised by referen ce to the recently refined X-ray crystal structure of the wild-type pa rticle.