PT  - JOURNAL ARTICLE
AU  - S Hormeno
AU  - OJ Wilkinson
AU  - C Aicart-Ramos
AU  - S Kuppa
AU  - E Antony
AU  - MS Dillingham
AU  - F Moreno-Herrero
TI  - Human HELB is a processive motor protein which catalyses RPA clearance from single-stranded DNA
AID  - 10.1101/2021.05.27.445972
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.05.27.445972
4099  - http://biorxiv.org/content/early/2021/05/27/2021.05.27.445972.short
4100  - http://biorxiv.org/content/early/2021/05/27/2021.05.27.445972.full
AB  - Human HELB is a poorly-characterised helicase suggested to play both positive and negative regulatory roles in DNA replication and recombination. In this work, we used bulk and single molecule approaches to characterise the biochemical activities of HELB protein with a particular focus on its interactions with RPA and RPA-ssDNA filaments. HELB is a monomeric protein which binds tightly to ssDNA with a site size of ∼20 nucleotides. It couples ATP hydrolysis to translocation along ssDNA in the 5′-to-3′ direction accompanied by the formation of DNA loops and with an efficiency of 1 ATP per base. HELB also displays classical helicase activity but this is very weak in the absence of an assisting force. HELB binds specifically to human RPA which enhances its ATPase and ssDNA translocase activities but inhibits DNA unwinding. Direct observation of HELB on RPA nucleoprotein filaments shows that translocating HELB concomitantly clears RPA from single-stranded DNA.Competing Interest StatementThe authors have declared no competing interest.