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Regulation of Streptococcus pneumoniae FtsZ assembly by divalent cations: paradoxical effects of Ca 2+ on the nucleation and bundling of FtsZ polymers
Author(s) -
Dhaked Hemendra Pal Singh,
Ray Shashikant,
Battaje Rachana Rao,
Banerjee Anirban,
Panda Dulal
Publication year - 2019
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.14928
Subject(s) - ftsz , gtpase , biophysics , gtp' , cytoskeleton , divalent , chemistry , cell division , peptidoglycan , guanosine triphosphate , microbiology and biotechnology , biology , biochemistry , cell wall , cell , organic chemistry , enzyme
The assembly and disassembly of the FtsZ ring drives the division of bacteria cells, including Streptococcus pneumoniae , which causes pneumonia and meningitis. In contrast to FtsZ from other bacterial species, Streptococcus pneumoniae ( Spn ) FtsZ contains two tryptophan residues. Here, we demonstrate that the assembly and disassembly of Streptococcus pneumoniae FtsZ ( Spn FtsZ) monomers can be monitored by the intrinsic tryptophan fluorescence of FtsZ. We found that the assembly of Spn FtsZ is closely associated with its GTPase activity. Guanosine 5′‐[β,γ‐imido]triphosphate, a nonhydrolyzable analog of GTP, stabilized the FtsZ filaments without inducing their bundling. Using intrinsic tryptophan fluorescence, light scattering, and electron microscopy, we could differentiate the effects of divalent calcium and magnesium on the assembly of FtsZ. Though Mg 2+ increased the stability of the FtsZ filaments, it could not prevent the disassembly of the filaments under conditions where GTP was limiting. Thus, our results indicate that Mg 2+ primarily enhances the longitudinal assembly of FtsZ. Low concentrations of Ca 2+ strongly promoted the bundling of FtsZ filaments and inhibited the disassembly of the filaments, suggesting that low concentrations of Ca 2+ enhance the lateral interactions between the FtsZ filaments. Interestingly, Ca 2+ delayed the nucleation process of FtsZ assembly, indicating that Ca 2+ exerts paradoxical effects on the assembly of FtsZ. However, higher concentrations of Ca 2+ did not enhance the bundling of FtsZ filaments. In addition, Ca 2+ altered the secondary structure of FtsZ and increased the fluorescence of the FtsZ‐1‐anilinonaphthalene‐8‐sulfonic acid complex, indicating that Ca 2+ induces conformational changes in FtsZ. The study provides an interesting insight into the assembly of Spn FtsZ and its regulation by divalent cations.