Table 1.

E. coli replisome components and associated functions

Replisome component		Subunit	Subunits/replisome	Molecules/cell	Gene	Mol. wt (kDa)	Function during DNA replication
Pol III H.E.	Pol III*	Pol III Core		20 (ref. in 109)			DNA synthesis and proofreading
		α	2		dnaE	129.9	DNA polymerase
		ε	2		dnaQ	27.5	3′–5′ exonuclease
		θ	2		holE	8.6	Stimulates exonuclease activity
		Clamp loader		(ref. in 97)			Clamp loading, stimulates helicase activity, connects leading and lagging strand polymerases, main coordinator of replisome
		γ/τ	3	140	dnaX	47.5/71.1	ATPase, connects both polymerases, interaction with DnaB
		δ	1	930	holA	38.7	Opens β clamp
		δ′	1	140	holB	36.9	Stator
		χ	1	1200	holC	16.6	Binds SSB
		ψ	1	340	holD	15.2	Connects clamp loader to SSB
		β	2	300 (ref. in 26)	dnaN	40.6	Processivity clamp
		Primase	3	50–100 (ref. in 135)	dnaG	65.6	RNA primer synthesis
		Helicase	6	15–20 (ref. in 133, 175)	dnaB	52.4	DNA unwinding
		SSB	4	800 (ref. in 141)	ssb	18.8	Binds ssDNA, prevents secondary structure formation, protects against nucleases, interacts with χ and primase