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1. DNA double helix, a tiny electromotor

   https://doi.org/10.1038/s41565-022-01285-z  

   Maffeo, Christopher; Quednau, Lauren; Wilson, James; Aksimentiev, Aleksei (December 2022, Nature Nanotechnology)

   Flowing fluid past chiral objects has been used for centuries to power rotary motion in man-made machines. By contrast, rotary motion in nanoscale biological or chemical systems is produced by biasing Brownian motion through cyclic chemical reactions. Here we show that a chiral biological molecule, a DNA or RNA duplex rotates unidirectionally at billions of revolutions per minute when an electric field is applied along the duplex, with the rotation direction being determined by the chirality of the duplex. The rotation is found to be powered by the drag force of the electro-osmotic flow, realizing the operating principle of a macroscopic turbine at the nanoscale. The resulting torques are sufficient to power rotation of nanoscale beads and rods, offering an engineering principle for constructing nanoscale systems powered by electric field. 

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2. Bridge Helix of Cas9 Modulates Target DNA Cleavage and Mismatch Tolerance

   https://doi.org/10.1021/acs.biochem.8b01241  

   Babu, Kesavan; Amrani, Nadia; Jiang, Wei; Yogesha, S.D.; Nguyen, Richard; Qin, Peter Z.; Rajan, Rakhi (March 2019, Biochemistry)
3. The bridge helix of Cas12a imparts selectivity in cis ‐DNA cleavage and regulates trans ‐DNA cleavage

   https://doi.org/10.1002/1873-3468.14051  

   Parameshwaran, Hari Priya; Babu, Kesavan; Tran, Christine; Guan, Kevin; Allen, Aleique; Kathiresan, Venkatesan; Qin, Peter Z.; Rajan, Rakhi (February 2021, FEBS Letters)

   Cas12a is an RNA‐guided DNA endonuclease of the type V‐A CRISPR‐Cas system that has evolved convergently with the type II Cas9 protein. We previously showed that proline substitutions in the bridge helix (BH) impart target DNA cleavage selectivity inStreptococcus pyogenes(Spy) Cas9. Here, we examined a BH variant of Cas12a fromFrancisella novicida(FnoCas12a^KD2P) to test mechanistic conservation. Our results show that for RNA‐guided DNA cleavage (cis‐activity), FnoCas12a^KD2Paccumulates nicked products while cleaving supercoiled DNA substrates with mismatches, with certain mismatch positions being more detrimental for linearization. FnoCas12a^KD2Palso possess reducedtrans‐single‐stranded DNA cleavage activity. These results implicate the BH in substrate selectivity in bothcis‐andtrans‐cleavages and show its conserved role in target discrimination among Cas nucleases. 

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4. Chiral Sum Frequency Generation Spectroscopy Detects Double-Helix DNA at Interfaces

   https://doi.org/10.1021/acs.langmuir.2c00365  

   Perets, Ethan A.; Olesen, Kristian B.; Yan, Elsa C. (April 2022, Langmuir)
5. Coordinated Actions of Cas9 HNH and RuvC Nuclease Domains Are Regulated by the Bridge Helix and the Target DNA Sequence

   https://doi.org/10.1021/acs.biochem.1c00354  

   Babu, Kesavan; Kathiresan, Venkatesan; Kumari, Pratibha; Newsom, Sydney; Parameshwaran, Hari Priya; Chen, Xiongping; Liu, Jin; Qin, Peter Z.; Rajan, Rakhi (November 2021, Biochemistry)