Novel polymorphism of recA fibrils revealed by Atomic Force Microscopy
Bernie D. Sattin and M. Cynthia Goh
RecA aggregates under physiological conditions have been successfully imaged using Tap-ping Mode atomic force microscopy. This represents the first time images of RecA have been obtained without drying, freezing and/or exposure to high vacuumconditions. While previously observed structures - the monomer, the hexamer, the short rod (fibril) - were seen, a new type of aggregate was also observed. This protofibril is narrower in diameter than the standard fibril, and occurs in three distinct morphologies: aperiodic, 100-nm periodic, and 150-nm periodic. In addition, much longer rods are observed, and appear curved and even circular.