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 genomic RNA, has been investigated using electron microscopy. Coat protein mutants with amino acid substitutions at residues involved in making contracts at both inter-molecular interfaces and within the coat protein submit are also capable of forming 'empty' capsids of the same size and symmetry as the wild-type protein. Mutations have been characterised which are neutral, deleterious or advantageous in terms of thermal stability. In some cases, the results can be rationalised by reference to the recently refined X-ray crystal structure of the wild-type particle.