Table 4.

Viral DNA helicases. AAV, Adeno‐associated virus; ACNP, Autographa californica nuclear polyhedrosis; BPV, bovine papilloma virus; HSV, herpes simplex virus; MVM NS1, minute virus of mice–nonstructural protein; nd, not determined; OBP, origin binding protein; SV40 T‐antigen, Simian virus 40 large T antigen; SARS‐CoV, severe acute respiratory syndrome coronavirus (Coronoviridae helicase).

S. No.	Name of helicase	Mol. mass (kDa)	Nucleotide cofactors	Polarity	Remarks
1	SV40 T‐antigen a	94	ATP > dATP >  dTTP = UTP	3′−5′	Interacts with DNA pol. α; essential for DNA replication; contains both DNA and RNA helicase activities.
2.	Polyoma T‐antigen b	100	ATP = dATP > CTP = UTP	3′−5′	Contains Polyoma ori binding and unwinding activities.
3.	HSV‐1. UL5/UL8/UL52 Complex c	120 97 70	ATP > GTP > CTP = UTP	5′−3′	UL5 and UL52 required for helicase‐primase activity.
4.	HSV‐1, UL9 protein d	68	ATP = dATP > CTP > dCTP	3′−5′	OBP involved during the initiation of HSV replication.
5.	BPV‐1, E1 protein e	68	ATP, dATP, CTP, dCTP, UTP, dTTP, GTP, dGTP	3′−5′	OBP, which is stimulated by E2 protein of BPV‐1.
6.	AAV, Rep68, Rep78 f	68 71	ATP > CTP > dATP > GTP > UTP	3′−5′	Contains site‐and strand‐specific endonuclease activity.
7.	AAV‐Rep52 g	52	ATP, dATP, CTP, dCTP, UTP, dTTP, GTP, dGTP	3′−5′	Lysine to histidine substitution within motif I was deficient for both DNA helicase and ATPase activities.
8.	AAV‐Rep40 h	40	ATP	3′−5′	Lysine to histidine mutation in the purine nucleotide‐binding site results in a protein that inhibits helicase activity.
9.	MVM NS‐1 i	83	ATP > dATP	nd	Appears to have site‐specific endonuclease activity.
10.	ACNP virus P143 j	143	ATP	nd	Stimulated by LEF3/SSB; essential for virus DNA replication.
11.	Vaccinia virus A18R k	57.5	ATP	3′−5′	It is a DExH box protein and is involved in transcription.
12	SARS‐CoV helicase l	70	ATP, dATP, CTP >  all others	5′−3′	Attractive target for anti‐SARS therapy.

^a [ 84]; ^b [85]; ^c [86]; ^d [87]; ^e [88]; ^f [89]; ^g [89]; ^h [89]; ⁱ [90]; ^j [91]; ^k [92]; ^l [93].