An ancient anion-binding structural module in RNA and DNA helicases.

ABSTRACT: RNA and DNA helicases manipulate or translocate along single strands of nucleic acids by grasping them using a conserved structural motif. We have examined the available crystal structures of helicases of the two principal superfamilies, SF1 and SF2, and observed that the most conserved interactions with the nucleic acid occur between the phosphosugar backbone of a trinucleotide and the three strand-helix loops within a (beta-strand/alpha-helix)(3) structural module. At the first and third loops is a conserved hydrogen-bonded feature called a thr-motif, often seen at alpha-helical N-termini, with the threonine as the N-cap residue. These loops can be aligned with few insertions or deletions, and their main chain atoms are structurally congruent amongst the family members and between the tw

SUBMITTER: Milner-White EJ 

PROVIDER: S-EPMC7610952 | biostudies-literature | 2010 Jun

REPOSITORIES: biostudies-literature