Letter to the editorThe capsid protein of bacteriophage lambda and of its prehead☆
Review articleOpen access
Thomas Hohn - No affiliation found
1976/08/05 Full-length article DOI: 10.1016/0022-2836(76)90117-0
Journal: Journal of Molecular Biology
AbstractSeveral complex DNA bacteriophages are formed by packing the genome into precapsids. In many of these cases the capsid enlarges during the packaging process (Casjens & King, 1975; Hohn et al., 1976; leading to further references). At least in bacteriophage λ this transition is conservative and main capsid subunits are neither added to, nor removed from the maturing precapsid (Hohn et al., 1974,1976; Kaiser et al., 1975). Thus the enlargement of the head is caused by a rearrangement of the subunits and/or a structural shift within each subunit. There is evidence that the transition from precapsid to capsid is unidirectional (Hohn et al., 1976), and such an irreversible process would be most easily understood if it is caused by a change or modification of primary structure of the subunit. In fact, in bacteriophages T5, P2 and T4, morphogenetic protein cleavage of the main capsid subunit was observed (for a review see Hershko & Fry, 1975). However, it is not yet clear whether this cleavage is the cause or the result of head enlargement and DNA filling.In bacteriophage λ protein cleavage of the major capsid protein (E-protein; pE) is not detectable by standard sodium dodecyl sulfate/acrylamide gel electrophoresis. To detect possible minor cleavages, in this study amino acid composition and end groups of precapsid and capsid protein were determined. Furthermore, it was checked whether glucosylation or phosphorylation of the capsid protein occurs. The study was extended to include pE from a further type of small capsid (Nu3− petit λ), which we suspect to have still another configuration than the prehead and the head (Hohn et al., 1975).
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