| Title: |
Different quaternary structures of human RECQ1 are associated with its dual enzymatic activity |
| Authors: |
Muzzolini, L; Beuron, F; Patwardhan, A; Popuri, V; Cui, S; Niccolini, B; Rappas, M; Freemont, PS; Vindigni, A |
| Source: |
168 ; 157 |
| Publisher Information: |
Public Library of Science (PLoS) |
| Publication Year: |
2006 |
| Collection: |
Imperial College London: Spiral |
| Subject Terms: |
Science & Technology; Life Sciences & Biomedicine; Biochemistry & Molecular Biology; Biology; Life Sciences & Biomedicine - Other Topics; BLOOMS-SYNDROME HELICASE; ESCHERICHIA-COLI RECQ; STRAND-ANNEALING ACTIVITIES; SYNDROME GENE-PRODUCT; DNA HELICASE; HOLLIDAY JUNCTIONS; SYNDROME PROTEIN; MONOMERIC HELICASE; CRYSTAL-STRUCTURES; MISMATCH REPAIR; Binding; Competitive; Chromatography; Gel; DNA; Humans; Microscopy; Electron; Protein Structure; Quaternary; RecQ Helicases |
| Description: |
RecQ helicases are essential for the maintenance of chromosome stability. In addition to DNA unwinding, some RecQ enzymes have an intrinsic DNA strand annealing activity. The function of this dual enzymatic activity and the mechanism that regulates it is, however, unknown. Here, we describe two quaternary forms of the human RECQ1 helicase, higher-order oligomers consistent with pentamers or hexamers, and smaller oligomers consistent with monomers or dimers. Size exclusion chromatography and transmission electron microscopy show that the equilibrium between the two assembly states is affected by single-stranded DNA (ssDNA) and ATP binding, where ATP or ATPγS favors the smaller oligomeric form. Our three-dimensional electron microscopy reconstructions of human RECQ1 reveal a complex cage-like structure of approximately 120 Å × 130 Å with a central pore. This oligomeric structure is stabilized under conditions in which RECQ1 is proficient in strand annealing. In contrast, competition experiments with the ATPase-deficient K119R and E220Q mutants indicate that RECQ1 monomers, or tight binding dimers, are required for DNA unwinding. Collectively, our findings suggest that higher-order oligomers are associated with DNA strand annealing, and lower-order oligomers with DNA unwinding. |
| Document Type: |
article in journal/newspaper |
| Language: |
English |
| Relation: |
PLoS Biology; http://hdl.handle.net/10044/1/69623; https://dx.doi.org/10.1371/journal.pbio.0050020 |
| DOI: |
10.1371/journal.pbio.0050020 |
| Availability: |
http://hdl.handle.net/10044/1/69623; https://doi.org/10.1371/journal.pbio.0050020 |
| Rights: |
© 2007 Muzzolini. This is an open-access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. |
| Accession Number: |
edsbas.446AB3D6 |
| Database: |
BASE |