The apo-form of the Vibrio cholerae replicative helicase DnaB is a labile and inactive planar trimer of dimers.
Cargemel, C., Walbott, H., Durand, D., Legrand, P., Ouldali, M., Ferat, J.L., Marsin, S., Quevillon-Cheruel, S.(2022) FEBS Lett 596: 2031-2040
- PubMed: 35568982 
- DOI: https://doi.org/10.1002/1873-3468.14403
- Primary Citation of Related Structures:  
7QXM - PubMed Abstract: 
To enable chromosomal replication, DNA is unwound by the ATPase molecular motor replicative helicase. The bacterial helicase DnaB is a ring-shaped homo-hexamer whose conformational dynamics are being studied through its different 3D structural states adopted along its functional cycle. Our findings describe a new crystal structure for the apo-DnaB from Vibrio cholerae, forming a planar hexamer with pseudo-symmetry, constituted by a trimer of dimers in which the C-terminal domains delimit a triskelion-shaped hole. This hexamer is labile and inactive. We suggest that it represents an intermediate state allowing the formation of the active NTP-bound hexamer from dimers.
Organizational Affiliation: 
CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, Gif-sur-Yvette, France.