A Decade of Biochemical and Structural Studies of the DNA Repair Machinery of Deinococcus radiodurans: Major Findings, Functional and Mechanistic Insight and Challenges

Abstract

The Deinococcus radiodurans bacterium is extremely resistant to ionising radiation and desiccation and can withstand a 200-fold higher radiation dose than most other bacteria with no loss of viability. The mechanisms behind this extreme resistance are not fully understood, but it is clear that several factors contribute to this phenotype. Efficient scavenging of reactive oxygen species and repair of damaged DNA are two of these. In this review, we summarise the results from a decade of structural and functional studies of the DNA repair machinery of Deinococcus radiodurans and discuss how these studies have contributed to an improved understanding of the molecular mechanisms underlying DNA repair and to the outstanding resistance of Deinococcus radiodurans to DNA damaging agents.

Fig. 1

Illustration of the structures of D. radiodurans proteins involved in DNA repair processes. All structures are presented in rainbow colours (N-termini in blue and C-termini in red). The following PDB codes were used to prepare the figures using Pymol : UNG (4uqm), MUG (2c2p), AlkA2 (2yg8), EndoIII-1 (4unf), EndoIII-3 (4uob), UvrA2 (2vf7), UvrD (4c2v), RecN (4aby; 4abx; 4ad8), RecA (1xp8), RecD2 (3e1s), RecF (2o5v), RecO (1w3s), RecR (1vdd), RecOR (4jcv) and RecQ (4q47).

Fig. 2

Examples of altered DNA repair processes in D. radiodurans. (A) RecA promoted DNA strand exchange in E. coli vs. D. radiodurans. Unlike E. coli RecA, drRecA assembles on dsDNA. (Figure adapted from .) (B) DNA unwinding by the UvrD helicase in E. coli vs. D. radiodurans. Unlike E. coli UvrD, drUvrD is a bipolar helicase; it unwinds both 3′- and 5′-tailed dsDNA.