Single-molecule studies of the effect of spermidine on DNA mechanics and viral DNA packaging

Nicholas Keller; Douglas E. Smith

doi:10.1117/12.930381

10 October 2012 Single-molecule studies of the effect of spermidine on DNA mechanics and viral DNA packaging

Nicholas Keller, Douglas E. Smith

Proceedings Volume 8458, Optical Trapping and Optical Micromanipulation IX; 845818 (2012) https://doi.org/10.1117/12.930381
Event: SPIE NanoScience + Engineering, 2012, San Diego, California, United States

Abstract

Polyamine ions such as spermidine³⁺, along with monovalent and divalent salt ions, screen the negatively charged backbone of dsDNA and thereby facilitate processes in which DNA is confined in small spaces, such as viral DNA packaging. We use optical tweezers to directly manipulate single DNA molecules and have made preliminary measurements of the effect of spermidine on DNA elasticity, condensation, and viral packaging. We determine the concentration of spermidine³⁺ at which dsDNA condenses in the presence of Mg²⁺ and Na⁺ and report a monotonic increase in stretch modulus and decrease in persistence length at incremental spermidine concentrations up to the concentration at which dsDNA condenses. We also discuss the effect of spermidine on DNA packaging in bacteriophage phi29.

Citation Download Citation

Nicholas Keller and Douglas E. Smith "Single-molecule studies of the effect of spermidine on DNA mechanics and viral DNA packaging", Proc. SPIE 8458, Optical Trapping and Optical Micromanipulation IX, 845818 (10 October 2012); https://doi.org/10.1117/12.930381

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