Postprint version. Published in Trends in Microbiology, Volume 14, Issue 8, August 1, 2006, pages 329-331. Copyright © 2006 Elsevier. The definitive version is available at http://dx.doi.org/10.1016/j.tim.2006.06.004.
Magnetotactic bacteria contain chains of magnetosomes that comprise a permanent magnetic dipole in each cell. In two separate, recent papers, Scheffel et al. and Komeili et al. describe the roles of the proteins MamJ and MamK in magnetosome chain formation. Here, we describe the two studies and highlight questions that must be addressed in future investigations of how magnetotactic bacteria construct their magnetic compass needles.