Structural biology: Proteobacterial accessories for diverse cellulose synthesis.

BcsD is broadly present throughout Proteobacteria and is predicted to contribute to cellulose crystallinity via interaction with BcsH. However, new work shows that, in non-crystalline forming Proteobacteria, BcsD contains an amino-terminal a1-helix, forms a tetrahedron-like structure, and interacts with alternative proline-rich protein partners.

E. coli RecB Nuclease Domain Regulates RecBCD Helicase Activity but not Single Stranded DNA Translocase Activity.

Much is still unknown about the mechanisms by which helicases unwind duplex DNA. Whereas structure-based models describe DNA unwinding as occurring by the ATPase motors mechanically pulling the DNA duplex across a wedge domain in the helicase, biochemical data show that processive DNA unwinding by E. coli RecBCD helicase can occur in the absence of ssDNA translocation by the canonical RecB and RecD motors.

How Does a Helicase Unwind DNA? Insights from RecBCD Helicase.

DNA helicases are a class of molecular motors that catalyze processive unwinding of double stranded DNA. In spite of much study, we know relatively little about the mechanisms by which these enzymes carry out the function for which they are named. Most current views are based on inferences from crystal structures.