Biology:FtsA

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Short description: Bacterial protein that is related to actin
Cell division protein FtsA
FtsA-GFP.jpg
E. coli cells producing FtsA-GFP, which localizes to the cell division site.
Identifiers
OrganismEscherichia coli (strain K12)
SymbolFtsA
Entrez944778
RefSeq (Prot)NP_414636.1
UniProtP0ABH0
Other data
ChromosomeGenome: 0.1 - 0.11 Mb
FtsA
Identifiers
SymbolFtsA
InterProIPR020823
SHS2 "1C" domain inserted in FtsA
Identifiers
SymbolSHS2_FtsA
PfamPF02491
InterProIPR003494
SMARTSM00842

FtsA is a bacterial protein that is related to actin by overall structural similarity and in its ATP binding pocket.[1][2][3]

Along with other bacterial actin homologs such as MreB, ParM, and MamK, these proteins suggest that eukaryotic actin has a common ancestry. Like the other bacterial actins, FtsA binds ATP and can form actin-like filaments.[4] The FtsA-FtsA interface has been defined by structural as well as genetic analysis.[5] Although present in many diverse Gram-positive and Gram-negative species, FtsA is absent in actinobacteria and cyanobacteria. FtsA also is structurally similar to PilM, a type IV pilus ATPase.[6]

Function

FtsA is required for proper cytokinesis in bacteria such as Escherichia coli, Caulobacter crescentus, and Bacillus subtilis. Originally isolated in a screen for E. coli cells that could divide at 30˚C but not at 40˚C,[7] FtsA stands for "filamentous temperature sensitive A". Many thermosensitive alleles of E. coli ftsA exist, and all map in or near the ATP binding pocket. Suppressors that restore normal function map either to the binding pocket or to the FtsA-FtsA interface.[8]

FtsA localizes to the cytokinetic ring formed by FtsZ (Z ring). One of FtsA's functions in cytokinesis is to tether FtsZ polymers to the cytoplasmic membrane via a conserved C-terminal amphipathic helix, forming an "A ring" in the process.[9] Removal of this helix results in the formation of very long and stable polymer bundles of FtsA in the cell that do not function in cytokinesis.[5] Another essential division protein, ZipA, also tethers the Z ring to the membrane and exhibits overlapping function with FtsA. FtsZ, FtsA and ZipA together are called the proto-ring because they are involved in a specific initial phase of cytokinesis.[10] Another subdomain of FtsA (2B) is required for interactions with FtsZ, via the conserved C-terminus of FtsZ.[4] Other FtsZ regulators including MinC and ZipA bind to the same C terminus of FtsZ. Finally, subdomain 1C, which is in a unique position relative to MreB and actin, is required for FtsA to recruit downstream cell division proteins such as FtsN.[11][12]

Although FtsA is essential for viability in E. coli, it can be deleted in B. subtilis. B. subtilis cells lacking FtsA divide poorly, but still survive. Another FtsZ-interacting protein, SepF (originally named YlmF; O31728), is able to replace FtsA in B. subtilis, suggesting that SepF and FtsA have overlapping functions.[13]

An allele of FtsA called FtsA* (R286W) is able to bypass the normal requirement for the ZipA in E. coli cytokinesis.[14] FtsA* also causes cells to divide at a shorter cell length than normal, suggesting that FtsA may normally receive signals from the septum synthesis machinery to regulate when cytokinesis can proceed.[15] Other FtsA*-like alleles have been found, and they mostly decrease FtsA-FtsA interactions.[5] Oligomeric state of FtsA is likely important for regulating its activity, its ability to recruit the later cell division proteins [5] and its ability to bind ATP.[8] Other cell division proteins of E. coli, including FtsN and the ABC transporter homologs FtsEX, seem to regulate septum constriction by signaling through FtsA,[16][17] and the FtsQLB subcomplex is also involved in promoting FtsN-mediated septal constriction.[18][19]

FtsA binds directly to the conserved C-terminal domain of FtsZ.[20][4] This FtsA-FtsZ interaction is likely involved in regulating FtsZ polymer dynamics. In vitro, E. coli FtsA disassembles FtsZ polymers in the presence of ATP, both in solution, as FtsA* [21] and on supported lipid bilayers.[22] E. coli FtsA itself does not assemble into detectable structures except when on membranes, where it forms dodecameric minirings that often pack in clusters and bind to single FtsZ protofilaments.[23] In contrast, FtsA* forms arcs on lipid membranes but rarely closed minirings, supporting genetic evidence that this mutant has a weaker FtsA-FtsA interface.[5] When bound to the membrane, FtsA*-like mutants, which also can form double-stranded filaments, enhance close lateral interactions between FtsZ protofilaments, in contrast to FtsA, which keeps FtsZ protofilaments apart.[24] As FtsZ protofilament bundling may be important for promoting septum formation, a switch from an FtsA-like to an FtsA*-like conformation during cell cycle progression may serve to turn on septum synthesis enzymes (FtsWI) as well as condense FtsZ polymers, setting up a positive feedback loop. In support of this model, the cytoplasmic domain of FtsN, which activates FtsWI in E. coli and interacts directly with the 1C subdomain of FtsA, switches FtsA from the miniring form to the double stranded filament form on lipid surfaces in vitro.[25] These double filaments of E. coli FtsA are antiparallel, indicating that they themselves do not treadmill like FtsZ filaments.

Although E. coli FtsA has been the most extensively studied, more is becoming understood about FtsA proteins from other species. FtsA from Streptococcus pneumoniae forms helical filaments in the presence of ATP,[26] but no interactions with FtsZ in vitro have been reported yet. FtsA colocalizes with FtsZ in S. pneumoniae, but also is required for FtsZ ring localization, in contrast to E. coli where FtsZ rings remain localized upon inactivation of FtsA. FtsA from Staphylococcus aureus forms actin-like filaments similar to those of FtsA from Thermotoga maritima. [27] In addition, S. aureus FtsA enhances the GTPase activity of FtsZ. In a liposome system, FtsA* stimulates FtsZ to form rings that can divide liposomes, mimicking cytokinesis in vitro.[28]

Structure

Several crystal structures for FtsA are known, including a structure for E. coli FtsA.[29] Compared to MreB and eukaryotic actin, the subdomains are rearranged, and the 1B domain is swapped out for the SHS2 "1C" insert.[4][30][1][31]

References

  1. ↑ 1.0 1.1 "Crystal structure of the cell division protein FtsA from Thermotoga maritima". The EMBO Journal 19 (20): 5300–7. Oct 2000. doi:10.1093/emboj/19.20.5300. PMID 11032797. 
  2. ↑ "The evolution of compositionally and functionally distinct actin filaments". Journal of Cell Science 128 (11): 2009–19. Jun 2015. doi:10.1242/jcs.165563. PMID 25788699. 
  3. ↑ "In search of the primordial actin filament". Proceedings of the National Academy of Sciences of the United States of America 112 (30): 9150–1. Jul 2015. doi:10.1073/pnas.1511568112. PMID 26178194. 
  4. ↑ 4.0 4.1 4.2 4.3 "FtsA forms actin-like protofilaments". The EMBO Journal 31 (10): 2249–60. May 2012. doi:10.1038/emboj.2012.76. PMID 22473211. 
  5. ↑ 5.0 5.1 5.2 5.3 5.4 "FtsA mutants impaired for self-interaction bypass ZipA suggesting a model in which FtsA's self-interaction competes with its ability to recruit downstream division proteins". Molecular Microbiology 83 (1): 151–67. Jan 2012. doi:10.1111/j.1365-2958.2011.07923.x. PMID 22111832. 
  6. ↑ "Structure of the PilM-PilN inner membrane type IV pilus biogenesis complex from Thermus thermophilus". The Journal of Biological Chemistry 286 (27): 24434–42. Jul 2011. doi:10.1074/jbc.M111.243535. PMID 21596754. 
  7. ↑ "Mutants thermosensibles d'Escherichia coli K12". Annales de l'Institute Pasteur 110 (4): 465–86. April 1966. 
  8. ↑ 8.0 8.1 "A thermosensitive defect in the ATP binding pocket of FtsA can be suppressed by allosteric changes in the dimer interface". Molecular Microbiology 94 (3): 713–27. Nov 2014. doi:10.1111/mmi.12790. PMID 25213228. 
  9. ↑ "Tethering the Z ring to the membrane through a conserved membrane targeting sequence in FtsA". Molecular Microbiology 55 (6): 1722–34. Mar 2005. doi:10.1111/j.1365-2958.2005.04522.x. PMID 15752196. 
  10. ↑ "In the beginning, Escherichia coli assembled the proto-ring: an initial phase of division". The Journal of Biological Chemistry 288 (29): 20830–6. Jul 2013. doi:10.1074/jbc.R113.479519. PMID 23740256. 
  11. ↑ "Role of two essential domains of Escherichia coli FtsA in localization and progression of the division ring". Molecular Microbiology 53 (5): 1359–71. Sep 2004. doi:10.1111/j.1365-2958.2004.04245.x. PMID 15387815. 
  12. ↑ "The early divisome protein FtsA interacts directly through its 1c subdomain with the cytoplasmic domain of the late divisome protein FtsN". Journal of Bacteriology 194 (8): 1989–2000. Apr 2012. doi:10.1128/JB.06683-11. PMID 22328664. 
  13. ↑ "A new FtsZ-interacting protein, YlmF, complements the activity of FtsA during progression of cell division in Bacillus subtilis". Molecular Microbiology 60 (6): 1364–80. Jun 2006. doi:10.1111/j.1365-2958.2006.05184.x. PMID 16796675. 
  14. ↑ "A gain-of-function mutation in ftsA bypasses the requirement for the essential cell division gene zipA in Escherichia coli". Proceedings of the National Academy of Sciences of the United States of America 100 (7): 4197–202. Apr 2003. doi:10.1073/pnas.0635003100. PMID 12634424. 
  15. ↑ "The ftsA* gain-of-function allele of Escherichia coli and its effects on the stability and dynamics of the Z ring". Microbiology 153 (Pt 3): 814–25. Mar 2007. doi:10.1099/mic.0.2006/001834-0. PMID 17322202. 
  16. ↑ "FtsEX acts on FtsA to regulate divisome assembly and activity". Proc Natl Acad Sci USA 113 (34): 5052–5061. Aug 2016. doi:10.1073/pnas.1606656113. PMID 27503875. 
  17. ↑ "The bypass of ZipA by overexpression of FtsN requires a previously unknown conserved FtsN motif essential for FtsA-FtsN interaction supporting a model in which FtsA monomers recruit late cell division proteins to the Z ring". Molecular Microbiology 95 (6): 971–987. Mar 2015. doi:10.1111/mmi.12907. PMID 25496259. 
  18. ↑ "A role for the FtsQLB complex in cytokinetic ring activation revealed by an ftsL allele that accelerates division". Molecular Microbiology 95 (6): 924–944. Mar 2015. doi:10.1111/mmi.12905. PMID 25496050. 
  19. ↑ "Roles for both FtsA and the FtsBLQ subcomplex in FtsN-stimulated cell constriction in Escherichia coli". Molecular Microbiology 95 (6): 945–970. Mar 2015. doi:10.1111/mmi.12906. PMID 25496160. 
  20. ↑ "Unique and overlapping roles for ZipA and FtsA in septal ring assembly in Escherichia coli.". EMBO Journal 21 (4): 685–93. 2002. doi:10.1093/emboj/21.4.685. PMID 11847116. 
  21. ↑ "Adenine nucleotide-dependent regulation of assembly of bacterial tubulin-like FtsZ by a hypermorph of bacterial actin-like FtsA". The Journal of Biological Chemistry 284 (21): 14079–86. May 2009. doi:10.1074/jbc.M808872200. PMID 19297332. 
  22. ↑ "The bacterial cell division proteins FtsA and FtsZ self-organize into dynamic cytoskeletal patterns". Nature Cell Biology 16 (1): 38–46. Jan 2014. doi:10.1038/ncb2885. PMID 24316672. 
  23. ↑ "Escherichia coli FtsA forms lipid-bound minirings that antagonize lateral interactions between FtsZ protofilaments". Nature Communications 8: 15957. July 2017. doi:10.1038/ncomms15957. PMID 28695917. 
  24. ↑ "Gain-of-function variants of FtsA form diverse oligomeric structures on lipids and enhance FtsZ protofilament bundling". Molecular Microbiology 109 (5): 676–693. September 2018. doi:10.1111/mmi.14069. PMID 29995995. 
  25. ↑ "Bacterial divisome protein FtsA forms curved antiparallel double filaments when binding to FtsN". Nature Microbiology 7 (10): 1686–1701. September 2022. doi:10.1038/s41564-022-01206-9. PMID 36123441. 
  26. ↑ "Cell division in cocci: localization and properties of the Streptococcus pneumoniae FtsA protein". Molecular Microbiology 55 (3): 699–711. 2005. doi:10.1111/j.1365-2958.2004.04432.x. PMID 15660997. https://iris.unitn.it/bitstream/11572/187538/1/Lara%20et%20al_%20Mol%20Microbiol_2005.pdf. 
  27. ↑ "Roles of the essential protein FtsA in cell growth and division in Streptococcus pneumoniae". Journal of Bacteriology 199 (3): e00608-16. February 2017. doi:10.1128/JB.00608-16. PMID 27872183. 
  28. ↑ "Liposome division by a simple bacterial division machinery". Proceedings of the National Academy of Sciences of the United States of America 110 (27): 11000–4. 2013. doi:10.1073/pnas.1222254110. PMID 23776220. 
  29. ↑ "Bacterial divisome protein FtsA forms curved antiparallel double filaments when binding to FtsN". Nature Microbiology 7 (10): 1686–1701. September 2022. doi:10.1038/s41564-022-01206-9. PMID 36123441. 
  30. ↑ "Crystal structure of FtsA from Staphylococcus aureus". FEBS Letters 588 (10): 1879–85. May 2014. doi:10.1016/j.febslet.2014.04.008. PMID 24746687. 
  31. ↑ "The SHS2 module is a common structural theme in functionally diverse protein groups, like Rpb7p, FtsA, GyrI, and MTH1598/TM1083 superfamilies". Proteins 56 (4): 795–807. September 2004. doi:10.1002/prot.20140. PMID 15281131. 



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