Table 1. Summary of the predicted essential phage functions in Sakai prophages.

Sakai Prophages	Repressor	Antirepressor	Integration/ Transposition1	Excision	Replication	General Recombination Function	Morphogenesis					DNA Packaging	Lysis
							Portal	Head	Major Tail	Minor Tail	Host Specificity
Possessing conserved lambdoid features
Sp3	−	−	D	+	−	D	D	−	+	+	+	+	+
Sp4	D	+	+	D	+	D	+	D	D	+	+	D	+
Sp5	+	+	+	+	+	+	+	U	U	U	U	+	+
Sp6	D	+	+	+	+	D	D	D	+	D	−	+	+
Sp8	−	−	+	+	+	−	+	+	+	+	+	+	+
Sp9	D	+	+	+	+	D	D	D	+	+	+	+	+
Sp10	D	+	+	+	+	+	+	+	+	+	+	+	+
Sp11	D	+	D	−	+	D	+	+	+	+	+	+	+
Sp12	D	+	D	+	+	D	D	D	+	+	D	+	+
Sp14	+	+	+	D	+	D	+	D	D	D	D	+	+
Sp15	+	+	+	+	+	D	+	−	+	+	D	+	+
P2- like prophage
Sp13	+	+	+	+	(+)	NA	−	−	−	D	−	−	−
P4- like prophage
Sp2	+	−	+	+	+	NA	NA2	NA2	NA2	NA2	NA2	NA2	NA2
Mu- like prophage
Sp18	+	NA	+	NA	+	+	+	+	+	+	(+)	+	+
Other
Sp1	+	+	D	−	D	−	−	−	−	−	−	−	−
Sp7	−	−	+	+	D	−	+	+	−	−	−	+	D
Sp16	−	−	+	−	D	−	−	−	+	−	−	−	−
Sp17	−	−	+	−	−	−	−	−	−	−	−	−	D

+, conserved; (+), atypical; D, defective; U, cannot be predicted; −, absent; NA, not applicable.

¹Applicable only for the Mu-like prophage.

²The morphogenesis and lysis functions of P4 are provided by the helper phage P2. The only morphogenesis function encoded on the P4 genome is the Sid, which determines the capsid size (Figure 1).