Ab initio maximum likelihood reconstruction of helical macromolecules using electron microscopy

Recent advance in cryo-electron microscopy allows structural determination of helical macromolecules without forming crystals. A conventional reconstruction method for helical structure is the Fourier-Bessel transform approach. However, this approach often fails in some instances such as flexible and disordered specimens. In order to overcome the drawbacks, a single particle reconstruction approach has been recently proposed. However, it often requires a good initial guess to guarantee the convergence. This paper describes an accurate model free maximum likelihood helical reconstruction algorithm by exploiting the symmetry and sparsity, which overcomes the drawbacks of the conventional methods.