Structure-Function Studies of the Magnetosom Associated Protein MamB - The Israel Society for Biochemistry & Molecular Biology (ISBMB) Abstract Submission Form

Noa Keren-Khadmy ¹ René Uebe ² Natalie Zeytuni ¹ Yotam Navon ³ Geula Davidov ¹ Dirk Schüler ² Ronit Bitton ³ Raz Zarivach ¹

¹Department of Life Sciences, Ben-Gurion University of the Negev and the National Institute for Biotechnology in the Negev, Beer-Sheva
²Department of Microbiology, University of Bayreuth, Bayreuth
³Department of Chemical Engineering, Ben-Gurion University of the Negev, Beer-Sheva

Cation diffusion facilitators (CDF) are proteins that maintain cellular divalent cation homeostasis in all domains of life. Magnetotactic bacteria (MTB) utilizing CDFs proteins during the magnetite biomineralization process in the magnetosom, a unique sub cellular organelle. Among the most abundant proteins associated with the magnetosome membrane of marine Magnetospira QH-2 is the CDF protein MamB. In this work we employed a multi-disciplinary approach to investigate MamB structure and function. Herein we present the crystal structure of the cytoplasmatic domain of MamB in its apo and zinc-bound forms which reveals new CDF-ion binding site position. MamB cytoplasmatic domain is folded into a metalochaperon-like fold and creates a stable dimer similar to other CDF-CTD’s. MamB is conserved both in its packing and in its fold. Crystal packing revealed a new type of interaction between CTDs monomers. Altogether, our results provide that MamB is not only involved in magnetosome formation but apparently also participant in iron accumulation.