Table 3.
Bacteriophage DNA helicases. nd, Not determined; PNA, peptide nucleic acid.
| S. No. | Name of helicase | Mol. mass (kDa) | Nucleotide cofactor | Polarity | Remarks |
|---|---|---|---|---|---|
| 1. | T4 gene 41 a | 58 | dGTP > ATP = dATP > GTP | 5′−3′ | Essential for both the priming and helicase activities. Stimulated by T4 gene 59 protein and forked 3′ tail substrate. |
| 2. | T4 dda b | 56 | ATP, dATP | 5′−3′ | Can also unwind DNA‐PNA substrate. Inhibited by T4 gene 32 protein involved in the DNA replication. Oligomerization of dda is not required for DNA unwinding. |
| 3. | T4 UvsW c | 65 | ATP | Nd | Catalyzes branch migration and is involved in recombination, repair and the regulation of DNA replication origin. |
| 4. | T7 gene 4 d | 56 and 63 | ATP, dATP dGTP,dTTP | 5′−3′ | 56 kDa protein contains DNA helicase activity, while 63 kDa (with 63 amino acids more) contains both the helicase and primase activities. |
| 5. | P4 gene α e | 84.9 | ATP, dATP GTP, dGTP CTP, dCTP | 3′−5′ | Stimulated by forked substrate, contains pri‐mase and sequence specific (5′‐TGTTCAC C −3′) binding activity of ori and crr DNA. |
| 6. | G40P f | 300 | ATP, GTP, CTP, UTP | 5′−3′ | Essential for B. subtilis bacteriophage SPP1 replication. |