Table 3.

Phenotypes of thirteen V163 mutants when expressed from plasmids.

Position 163 amino acid	Complementation efficiency*	Complementation score#	Recovered as viable phage	Prohead production§
Val	= 1.0	+	(wt)	+
Ile	1.0	+	+	+
Thr	1.0	+	+	+
Gln	1.0	+	+	+
Cys	1.0	+	+	+
Ala	1.0	+	+	+
Leu	0.1	+	+	+
Met	0.03	−	−	+
Asn	0.001	−	−	+
Ser	0.001	−	−	+
Phe	0.00003	−	−	+
Gly	0.00001	−	−	+
Glu	0.00001	−	−	+
Asp	0.00001	−	−	+

^*Complementation was done with HK97 phage bearing an amber mutation in gene 5 on a lawn of bacteria with a plasmid expressing the named V163X variant. The efficiency reported is calculated relative to the complementation achieved when using the wild-type plasmid, which is set to “1”.

^#Complementation of 0.1 or higher was judged to be “+”, lower than 0.1 as “–”.

^§Prohead production was determined in small scale cultures after induction of gene expression from a plasmid carrying the wild-type gene 4 and the named V163X variant of gene 5.