From Magnetosomes to Vesicles: LemA Proteins as Drivers of Bacterial Membrane Reorganization
The cellular machineries that remodel bacterial membranes during organelle and vesicle formation remain poorly defined. Herein, we report MamQ as a key determinant of the lipid invaginations that enclose the magnetosome. MamQ belongs to the broadly conserved LemA protein family, whose members localize to either the inner or outer membrane. Heterologous overproduction of 13 different LemA proteins…
Magnetosome membrane reorganization relies on LemA proteins, which are found in bacterial cells. These proteins, such as MamQ, are part of a family that can be located on either the inner or outer membrane. When these proteins are overproduced in E. coli, membrane reorganization and vesiculation occur, suggesting their role in membrane remodeling.
In P. aeruginosa, LemA1 (PaLemA1), an inner membrane protein, induces cytoplasmic membrane vesicle (CMV) formation, while the periplasmic-located outer membrane-anchored LemA2 (PaLemA2) drives the creation of bacterial outer-membrane vesicles (OMVs). Deleting the corresponding genes results in fewer extracellular vesicles. PaLemA1 and PaLemA2 interact with numerous cellular components, including those involved in cell division, such as CpoB, FtsE, FtsI, FtsK, FtsN, FtsW, MinE, ParB, ZapG, and ZipA.
PaLemA2 also interacts with the ESCRT-III-like protein PspA, which is involved in membrane remodeling.
Additional interaction partners include proteins involved in cell wall metabolism, membrane turnover, LPS biogenesis, protein export and maturation, energy metabolism, and stress-responsive gene regulation. These findings suggest that LemA proteins, in conjunction with PspA, CpoB, and divisome components, orchestrate membrane-localized protein complexes necessary for bacterial organelle biogenesis and vesicle formation.
They do this through a protein-machinery-driven mechanism that operates independently of passive chemical blebbing or lytic membrane fragmentation.
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