High-resolution structure of the E.coli RecQ helicase catalytic core

Abstract

RecQ family helicases catalyze critical genome maintenance reactions in bacterial and eukaryotic cells, playing key roles in several DNA metabolic processes. Mutations in recQ genes are linked to genome instability and human disease. To define the physical basis of RecQ enzyme function, we have determined a 1.8 Å resolution crystal structure of the catalytic core of Escherichia coli RecQ in its unbound form and a 2.5 Å resolution structure of the core bound to the ATP analog ATPγS. The RecQ core comprises four conserved subdomains; two of these combine to form its helicase region, while the others form unexpected Zn2+‐binding and winged‐helix motifs. The structures reveal the molecular basis of missense mutations that cause Bloom's syndrome, a human RecQ‐associated disease. Finally, based on findings from the structures, we propose a mechanism for RecQ activity that could explain its functional coordination with topoisomerase III.

On helicases and other motor proteins

“…In the case of UvrB [76] and RecQ [77], the site architecture and the relative positions of the subdomains are nearly indistinguishable regardless of the nucleotide bound at the ATP site. The best structural example of significantly distinguishable site types and correlated interdomain (or rather intersubunit) movements for a glutamine-tethered site is the structure of T7gp4 where the differences between 'ATP' and 'empty' states are readily apparent [36 ].…”

“…As a result, the 'tight' ATP-type interactions are generally not observed structurally when a glutamine is present in this position. Furthermore, the interaction of this glutamine with the other side of the site often seems to be mediated by additional residues as demonstrated by the structures of SF2 helicases Hepatitis C Virus NS3, UvrB [23, 75,76], and RecQ [77]. This configuration also appears to be present in the SF4 helicases T7gp4 [36 ] and DnaB [32 ].…”

Developing master keys to brain pathology, cancer and aging from the structural biology of proteins controlling reactive oxygen species and DNA repair

“…The classical seven helicase sequence motifs (I, Ia, II, III, IV, V & VI) which couple nucleotide triophosphate (NTP) binding and hydrolysis with unwinding nucleotide duplexes, are conserved. Motifs I and II (the walker A and B motifs) interact with the non-hydrolyzable ATP analog, ATP-γ-S and Mg 2+ in co-crystal structure of E. coli RecQ with these moieties (Bernstein et al, 2003) (Fig. 6e) and this is similar to SF1 & 2 helicases.…”

“…Important insights into the molecular mechanisms of WRN have also been discovered from the structure of the conserved RecQ helicase core from the E. coli homologue (Bernstein et al, 2003). The RecQ crystal structure revealed the presence of four domains in the helicase core (Fig.…”

Erratum to: Structure and Mechanisms of SF1 DNA Helicases

“…Helicase motifs involved in ATP binding are located at the interface between two RecA-like domains [43,46,47,95,96,101] in the structures of SF1 and SF2 helicases [48, [102][103][104]. Figure 2.2 shows the conserved sequence of the motifs (Q, I, Ia, II, III, IV, V, and VI) of the SF1 helicase family and their location in PcrA.…”