The crossing point values (Cp) were converted to absolute copies of cDNA using standard curves. The relative expressions of the target genes were calculated by dividing the absolute number of copies of cDNA by that of the reference gene rpoc (which encodes AZD6244 clinical trial RNA polymerase subunit ß’) in the same batch reactions. The primer sequences for qPCR are listed in Additional file 4: Table S2. Acknowledgments This study was supported by the National Natural Science Foundation of China (Grant No. 30970041

and 31270093) and the Undergraduate Student Innovation Program of China Agricultural University (Grant No. 2010-BKS-16). The authors thank Dr. Xin Gao (Testing Center, University of Science and Tucidinostat datasheet Technology of China) for the HR-TEM observations, and Dr. S. Anderson for English editing of the manuscript. Electronic supplementary material Additional file 1: Figure S1: Alignments of MamX in five MTB strains. M. magneticum AMB-1 (amb1017), M. magnetotacticum MS-1 (MMMS1v1_36310026), M. gryphiswaldense MSR-1 (MGR_4149), Magnetococcus

sp. MC-1 (Mmc1_2238), and Magnetovibrio MV-1 (mv1g00028). Identical residues are highlighted in dark gray and less conserved residues in light gray. The two boxes indicate two conserved CXXCH heme-binding motifs that are typical of c-type cytochromes in MamX. (DOCX 1 MB) Additional file 2: Figure S2: Predicted interactions among MamX, MamY, MamZ, FtsZ-like, and related proteins. See Discussion/ “The four proteins encoded by the mamXY operon …” for details. Top: mamXY organized as a whole operon with the same promoter. Middle: molecular weights of MamXY proteins in MSR-1. Bottom: PND-1186 bioinformatic

prediction of interactions within and outside of MamXY of MSR-1. The network nodes are proteins (green, MamY; brown, MamX; pink, MamZ; red, FtsZ-like; white, MamXY-associated proteins). The lines between two nodes represent predicted associations between two proteins. Stronger associations are represented by thicker lines. (DOCX 720 KB) Additional file 3: Table S1: Predicted proteins mafosfamide associated with FtsZ-like in MSR-1, and the corresponding homolog proteins in M. magneticum AMB-1. (DOCX 17 KB) Additional file 4: Table S2: Primer sequences used for quantitative real-time RT-PCR (qPCR). (DOCX 15 KB) References 1. Komeili A: Molecular mechanisms of compartmentalization and biomineralization in magnetotactic bacteria. FEMS Microbiol Rev 2012, 36:232–255.PubMedCrossRef 2. Jogler C, Schüler D: Genomics, genetics, and cell biology of magnetosome formation. Annu Rev Microbiol 2009, 63:501–521.PubMedCrossRef 3. Bazylinski DA, Frankel RB: Magnetosome formation in prokaryotes. Nat Rev Microbiol 2004, 2:217–230.PubMedCrossRef 4. Grunberg K, Wawer C, Tebo BM, Schüler D: A large gene cluster encoding several magnetosome proteins is conserved in different species of magnetotactic bacteria.