biostudies-literatureYang SNHLBI NIH HHSNIAMS NIH HHS45-54https://www.ebi.ac.uk/biostudies/studies/S-EPMC4696882biostudies-literatureUnknown193(1)Single particle analysis is widely used for three-dimensional reconstruction of helical filaments. Near-atomic resolution has been obtained for several well-ordered filaments. However, it is still a challenge to achieve high resolution for filaments with flexible subunits and a large axial rise per subunit relative to pixel size. Here, we describe an approach that improves the resolution in such cases. In filaments with a large axial rise, many segments must be shifted a long distance along the filament axis to match with a reference projection, potentially causing loss of alignment accuracy and hence resolution. In our study of myosin filaments, we overcame this problem by pre-determining the axial positions of myosin head crowns within segments to decrease the alignment error. In additioJournal of structural biologyAn approach to improve the resolution of helical filaments with a large axial rise and flexible subunits.PMC4696882R01 AR034711P01 HL059408R01 AR067279R01 AR062279Craig RYang SWoodhead JLZhao FQSulbaran GfalseAn approach to improve the resolution of helical filaments with a large axial rise and flexible subunits.Single particle analysis is widely used for three-dimensional reconstruction of helical filaments. Near-atomic resolution has been obtained for several well-ordered filaments. However, it is still a challenge to achieve high resolution for filaments with flexible subunits and a large axial rise per subunit relative to pixel size. Here, we describe an approach that improves the resolution in such cases. In filaments with a large axial rise, many segments must be shifted a long distance along the filament axis to match with a reference projection, potentially causing loss of alignment accuracy and hence resolution. In our study of myosin filaments, we overcame this problem by pre-determining the axial positions of myosin head crowns within segments to decrease the alignment error. In additio2016-01-01T00:00:00Z2016 Jan2026-05-05T08:09:25.578Z2019-03-27T02:06:02ZS-EPMC46968822659247310.1016/j.jsb.2015.11.007