Cation diffusion facilitators (CDF) are highly conserved, metal ion efflux transporters that maintain divalent transition metal cation homeostasis. Most CDF proteins contain two domains, the cation transporting transmembrane domain and the regulatory cytoplasmic C-terminal domain (CTD). MamM is a magnetosome-associated CDF protein essential for the biomineralization of magnetic iron-oxide particles in magnetotactic bacteria. To investigate the structure-function relationship of CDF cytoplasmic domains, we characterized a MamM M250P mutation that is synonymous with the disease-related mutation L349P of the human CDF protein ZnT-10. Our results show that the M250P exchange in MamM causes severe structural changes in its CTD resulting in abnormal reduced function. Our in vivo, in vitro and in silico studies indicate that the CTD fold is critical for CDF proteins' proper function and support the previously suggested role of the CDF cytoplasmic domain as a CDF regulatory element. Based on our results, we also suggest a mechanism for the effects of the ZnT-10 L349P mutation in human.
Bibliographical noteFunding Information:
This work was supported by the Israel Science Foundation (grant No. 761676), the Israel Ministry of Science, Technology and Space, Deutsche Forschungsgemeinschaft (SCHU 1080/13-1), the European Molecular Biology Organization and CMST COST Action CM1306. The research leading to these results has received funding from the European Communitys Seventh Framework Programme (FP7/20072013) under grant agreement no. 226716.
© The Author(s) 2016.