Identification of flexible Pif1–DNA interactions and their impacts on enzymatic activities. Issue 12 (24th June 2022)

• Record Type: Journal Article
• Authors: Li, Jinghua; Ma, Jianbing; Kumar, Vikash; Fu, Hang; Xu, Chunhua; Wang, Shuang; Jia, Qi; Fan, Qinkai; Xi, Xuguang; Li, Ming; Liu, Haiguang; Lu, Ying
• Is Part Of: Nucleic acids research. Volume 50:Issue 12(2022)
• Page Start: 7002
• Page End: 7012
• Publication Date: 2022-06-24
• Subjects: Nucleic acids -- Periodicals; Molecular biology -- Periodicals; 572.805
• DOI: 10.1093/nar/gkac529
• Languages: English
• ISSNs: 0305-1048

Abstract

Abstract: Flexible regions in biomolecular complexes, although crucial to understanding structure–function relationships, are often unclear in high-resolution crystal structures. In this study, we showed that single-molecule techniques, in combination with computational modeling, can characterize dynamic conformations not resolved by high-resolution structure determination methods. Taking two Pif1 helicases (ScPif1 and BsPif1) as model systems, we found that, besides a few tightly bound nucleotides, adjacent solvent-exposed nucleotides interact dynamically with the helicase surfaces. The whole nucleotide segment possessed curved conformations and covered the two RecA-like domains of the helicases, which are essential for the inch-worm mechanism. The synergetic approach reveals that the interactions between the exposed nucleotides and the helicases could be reduced by large stretching forces or electrostatically shielded with high-concentration salt, subsequently resulting in reduced translocation rates of the helicases. The dynamic interactions between the exposed nucleotides and the helicases underlay the force- and salt-dependences of their enzymatic activities. The present single-molecule based approach complements high-resolution structural methods in deciphering the molecular mechanisms of the helicases.