Spiroplasma membrane lipids

Davis, Philip J.; Katznel, A; Razin, Shmuel; Rottem, Shlomo

doi:10.1128/jb.161.1.118-122.1985

Cited by 22 publications

(8 citation statements)

References 25 publications

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“…Hence, we made single (ScMreB5 I95A and ScMreB5 W96A ) and double (ScMreB5 I95A,W96A ) mutant constructs of these residues of ScMreB5 WT ( Fig. S3 ) and tested their binding using liposomes having lipid composition resembling the S. citri membrane ( Davis et al, 1985 ). Before the addition of liposomes, the protein samples were spun at 21,500 g to ensure that any protein aggregates were removed.…”

Section: Resultsmentioning

confidence: 99%

Filament organization of the bacterial actin MreB is dependent on the nucleotide state

Pande

Mitra

Bagde

et al. 2022

Journal of Cell Biology

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MreB, the bacterial ancestor of eukaryotic actin, is responsible for shape in most rod-shaped bacteria. Despite belonging to the actin family, the relevance of nucleotide-driven polymerization dynamics for MreB function is unclear. Here, we provide insights into the effect of nucleotide state on membrane binding of Spiroplasma citri MreB5 (ScMreB5). Filaments of ScMreB5WT and an ATPase-deficient mutant, ScMreB5E134A, assemble independently of the nucleotide state. However, capture of the filament dynamics revealed that efficient filament formation and organization through lateral interactions are affected in ScMreB5E134A. Hence, the catalytic glutamate functions as a switch, (a) by sensing the ATP-bound state for filament assembly and (b) by assisting hydrolysis, thereby potentially triggering disassembly, as observed in other actins. Glu134 mutation and the bound nucleotide exhibit an allosteric effect on membrane binding, as observed from the differential liposome binding. We suggest that the conserved ATP-dependent polymerization and disassembly upon ATP hydrolysis among actins has been repurposed in MreBs for modulating filament organization on the membrane.

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Section: Resultsmentioning

confidence: 99%

Filament organization of the bacterial actin MreB is dependent on the nucleotide state

Pande

Mitra

Bagde

et al. 2022

Journal of Cell Biology

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“…In order to decipher mechanistic details of ScMreB5-liposome interaction, we carried out a lipid specificity study. S. citri membrane consists of ~38% phosphatidylglycerol (DOPG, an anionic lipid) and ~14% phosphatidylcholine (DOPC, a neutral lipid) (35).…”

Section: Scmreb5mentioning

confidence: 99%

“…4C, 4D) (34). Hence, we made single (ScMreB5 I95A and ScMreB5 W96A ) and double mutant (ScMreB5 I95A,W96A ) constructs of these residues of ScMreB5 WT and tested their binding using liposomes having lipid composition resembling S. citri membrane (35). In comparison to ScMreB5 WT , the mutations did not abrogate liposome binding significantly.…”

Section: Scmreb5mentioning

confidence: 99%

Filament dynamics driven by ATP hydrolysis modulates membrane binding of the bacterial actin MreB

Pande

Mitra

Bagde³

et al. 2021

Preprint

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MreB, the bacterial ancestor of eukaryotic actin, is responsible for shape in most rod- shaped bacteria. While the eukaryotic actin utilizes ATP hydrolysis to drive filament treadmilling, the relevance of nucleotide-driven polymerization dynamics for MreB function is unclear. Here, we report mechanistic insights into the interplay between nucleotide-binding, ATP hydrolysis and membrane-binding of Spiroplasma citri MreB5 (ScMreB5). Antiparallel double protofilament assembly of ScMreB5WT with ATP, ADP or AMPPNP and an ATPase deficient mutant ScMreB5E134A demonstrate that the filaments assemble independent of ATP hydrolysis. However, capture of the filament dynamics revealed that efficient filament formation, bundling through lateral interactions and filament disassembly are affected in ScMreB5E134A. Hence, the catalytic glutamate (Glu134 in ScMreB5) plays a dual role - it functions as a switch by sensing the ATP-bound state for filament assembly, and by assisting hydrolysis for triggering disassembly. Glu134 mutation also exhibits an allosteric effect on membrane binding, as observed from the reduced liposome binding compared to that of the wild type. Thus, ATP hydrolysis can modulate filament length and bundling, and consequently the orientation of MreB filaments on the cell membrane depending on the curvature. Binding of ScMreB5 with liposomes is mediated by surface charge-based interactions, demonstrating paralog and organism specific features for MreB function. We conclude that the conserved ATP-dependent polymerization and disassembly upon ATP hydrolysis has been repurposed for modulating curvature-dependent organization of filaments on the membrane.

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“…Mcap cells are coccoid and their genome does not encode any fibril or MreB protein. In addition, Mcap and Spiroplasma membranes have a similar lipid composition (Davis et al, 1985;Rottem, 1980), an essential point when considering that cytoskeleton elements were found to be closely associated with the membrane (Trachtenberg et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Tuning spherical cells into kinking helices in wall-less bacteria

Lartigue¹,

Lambert²,

Rideau³

et al. 2021

Preprint

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In bacteria, cell shape is determined and maintained through a complex interplay between the peptidoglycan cell wall and cytoplasmic filaments made of polymerized MreB. Spiroplasma species, members of the Mollicutes class, challenge this general understanding because they are characterized by a helical cell shape and motility without a cell wall. This specificity is thought to rely on five MreB isoforms and a specific fibril protein. In this study, combinations of these five MreBs and of the fibril from Spiroplasma citri were expressed in another Mollicutes, Mycoplasma capricolum. Mycoplasma cells that were initially pleomorphic, mostly spherical, turned into helices when MreBs and fibrils were expressed in this heterologous host. The fibril protein was essential neither for helicity nor for cell movements. The isoform MreB5 had a special role as it was sufficient to confer helicity and motility to the mycoplasma cells. Cryo-electron microscopy confirmed the association of MreBs and fibril-based cytoskeleton with the plasma membrane, suggesting a direct effect on the membrane curvature. Finally, the heterologous expression of these proteins, MreBs and fibril, made it possible to reproduce the kink-like motility of spiroplasmas without providing the ability of cell movement in liquid broth. We suggest that other Spiroplasma components, not yet identified, are required for swimming, a hypothesis that could be evaluated in future studies using the same model.

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Spiroplasma membrane lipids

Cited by 22 publications

References 25 publications

Filament organization of the bacterial actin MreB is dependent on the nucleotide state

Filament organization of the bacterial actin MreB is dependent on the nucleotide state

Filament dynamics driven by ATP hydrolysis modulates membrane binding of the bacterial actin MreB

Tuning spherical cells into kinking helices in wall-less bacteria

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