Switch-like control of helicase processivity by single-stranded DNA binding protein

eLife

Alice Troitskaia¹  Steve Yeo¹  Sei Sho²  Masayoshi Honda²  Maria Spies²  Barbara Stekas³  Yann R Chemla³ 

[1] Center for Biophysics and Quantitative Biology, University of Illinois, Urbana-Champaign, Urbana, United States;Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, United States;Department of Physics, University of Illinois, Urbana-Champaign, Urbana, United States;

关键词: helicase;    optical tweezers;    single molecule;    dna repair;    single-stranded DNA binding protein;   

DOI  :  10.7554/eLife.60515

来源: DOAJ

【 摘 要 】

Helicases utilize nucleotide triphosphate (NTP) hydrolysis to translocate along single-stranded nucleic acids (NA) and unwind the duplex. In the cell, helicases function in the context of other NA-associated proteins such as single-stranded DNA binding proteins. Such encounters regulate helicase function, although the underlying mechanisms remain largely unknown. Ferroplasma acidarmanus xeroderma pigmentosum group D (XPD) helicase serves as a model for understanding the molecular mechanisms of superfamily 2B helicases, and its activity is enhanced by the cognate single-stranded DNA binding protein replication protein A 2 (RPA2). Here, optical trap measurements of the unwinding activity of a single XPD helicase in the presence of RPA2 reveal a mechanism in which XPD interconverts between two states with different processivities and transient RPA2 interactions stabilize the more processive state, activating a latent ‘processivity switch’ in XPD. A point mutation at a regulatory DNA binding site on XPD similarly activates this switch. These findings provide new insights on mechanisms of helicase regulation by accessory proteins.

【 授权许可】

Unknown