1A-05 Temperature-dependent involvement of genel in the growth of bacteriophage φ29： analysis of the functions and the structure of genel product using mutant phages

Genel product (gp1) of bacteriophage φ29 is essential for efficient φ29 growth at high temperature (>42℃), although it is almost dispensable at low temperature (3O℃). For analyses of functions and structure of gp1, we constructed nine φ29 phages each bearing a different mutation which substitutes single amino acid in well-conserved regions of gp1. When propagation of phages were studied in one step growth, all the φ29 variants were able to grow at 30℃. However growth of the variants at 42℃ was differentially inhibited depending on the regions of the amino acid substitutions in gp1： Almost complete inhibition by substitutions in the coiled-coil region, partial inhibition by substitutions in the hydrophobic region near carboxyl terminus, and no detectable inhibition by substitutions in the amino terminal conserved region. Essentially the same inhibition pattern was observed for replication of φ29 genome as assessed by PCR. The coiled-coil and the hydrophobic regions are known to be essential for self-association of gp1 in vitro. Therefore we will further investigate whether the self-association of gp1 is required for the growth of φ29 under the high temperature culture condition.