Regulates the dynamic behavior of MamK filaments; paralog MamJ also promotes MamK turnover. At least one other protein besides MamJ and LimJ is required for MamK turnover (PubMed:21883528). Might connect magnetosomes to MamK filaments (Probable). Tagged protein extends in a line from one pole to the other. The center of the protein is Glu- and Pro-rich. Single gene deletion, no effect on magnetic response, the magnetosome chain or MamK filaments. A double mamJ/limJ deletion has wild-type magnetic response, but forms large gaps in the magnetosome chains reminiscent of the mamK deletion. MamK forms bundles in these gaps, but the MamK filaments are no longer dynamic. This bacteria makes up to 20 cubo-octahedral magnetosomes of about 45 nm in diameter which contain membrane-bound crystals of magnetite (Fe(3)O(4)). Belongs to the magnetosome MamJ protein family.