Cross-linking proteomics analysis for reliable identification of MamXY-associated magnetosome formation.

Magnetotactic bacteria (MTB) are a diverse group of prokaryotes capable of sensing geomagnetic fields through intracellular, membrane-enveloped magnetic organelles known as magnetosomes. In Magnetospirillum gryphiswaldense MSR-1, the mamXY operon encodes MamY, MamX, MamZ, and FtsZ-like protein, which are associated with magnetosome maturation through coordinated protein assembly. In this study, we performed a comparative analysis of protein association patterns related to the MamXY complex in wild-type (WT) and ftsZ-like overexpressing (overexp-ftsZ-like) strains using a modified SDS/boiling method with BS2G-d0/d4 cross-linking and liquid chromatography–tandem mass spectrometry (LC–MS/MS). The MamXY-associated protein profiles exhibited more regular and coordinated abundance patterns in the overexp-ftsZ-like strain compared to WT, and FtsZ-like overexpression was also associated with alterations in basal metabolic pathways. Comprehensive relative protein abundance profiling across different magnetic response states identified 47 differentially abundant proteins with consistent trends between the two strains. Among these, 10 magnetosome membrane proteins showed strong association with MamXY-related magnetosome formation, particularly during the protein recruitment stage, as supported by proteotypic peptide analysis. Together, our results provide a protein association-level framework for understanding MamXY-associated magnetosome formation and highlight coordinated protein patterns that may contribute to magnetosome morphology and size, warranting further functional validation.