Table 1.
Historical background of DNA helicases.
| Year | Discovery |
|---|---|
| 1953–76 | Prehelicase years |
| 1953 | Duplex structure of DNA was solved [55] |
| 1967 | Rep protein was the first helicase in E. coli to be identified by genetic criteria [56] |
| 1976 | Hoffman‐Berling isolated first DNA helicase (helicase I, a traI gene product) from E. coli[9] |
| 1978 | Existence of the first eukaryotic DNA helicase was reported from the lily [10] |
| 1979 | E. coli Rep protein was shown to contain DNA helicase activity [57] |
| 1982 | First bacteriophage protein reported as DNA helicase was T4 gene 41protein [11] |
| 1982–83 | A direct biochemical assay (strand displacement assay) for measuring helicase activity was developed [11, 12] |
| 1985 | First mammalian DNA helicase was reported from calf thymus [58] |
| 1986 | First viral encoded protein reported as DNA helicase was SV40 large tumor antigen [59] |
| First yeast protein reported as DNA helicase was ATPase III [60] | |
| 1988 | Hodgeman and Gorbalenya discovered helicase motifs (seven conserved amino acid domains) [9, 61] |
| 1989 | Two helicase superfamilies (SF1 and SF2) were reported [62] |
| DEAD box helicase family was identified [7] | |
| 1990 | First human DNA helicase (HDH) reported in the purified form [63] |
| E. coli RecQ protein was reported as DNA helicase [43] | |
| 1992 | First mitochondrial DNA helicase was isolated from bovine brain [64] |
| 1996 | First chloroplast DNA helicase was reported in the purified form from the pea [65] |
| Crystallization of First DNA helicase (PcrA from thermophilic bacterium) was reported [66] | |
| 1997 | Mcm4/6/7 protein complex from HeLa cells was reported as a DNA helicase [37] |
| Werner syndrome protein (WRN) was reported as a DNA helicase [67] | |
| Bloom's syndrome (BLM) gene product was reported as a DNA helicase [68] | |
| 1998 | Sgs1 (slow growth suppressor), a RecQ helicase from yeast, was reported as a DNA helicase [69] |
| 2000 | First plant DNA helicase gene (PDH45) encoding the biochemically active enzyme was cloned [30] |
| First eIF‐4A (from pea) was reported as a DNA helicase [30] | |
| 2002 | First biochemically active malarial parasite DNA helicase was reported [34] |
| 2003 | A new helicase motif (Q motif) was identified in DEAD box helicases [8] |
| Presence of Helitron insertion, a DNA helicase bearing transposable element, reported from maize genome [70] |