Limits...
Localisation of DivIVA by targeting to negatively curved membranes.

Lenarcic R, Halbedel S, Visser L, Shaw M, Wu LJ, Errington J, Marenduzzo D, Hamoen LW - EMBO J. (2009)

Bottom Line: In mutants with aberrant cell shapes, DivIVA accumulates where the cell membrane is most strongly curved.On the basis of electron microscopic studies and other data, we propose that this is due to molecular bridging of the curvature by DivIVA multimers.A Monte-Carlo simulation study showed that molecular bridging can be a general mechanism for binding of proteins to negatively curved membranes.

View Article: PubMed Central - PubMed

Affiliation: Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle upon Tyne, UK.

ABSTRACT
DivIVA is a conserved protein in Gram-positive bacteria and involved in various processes related to cell growth, cell division and spore formation. DivIVA is specifically targeted to cell division sites and cell poles. In Bacillus subtilis, DivIVA helps to localise other proteins, such as the conserved cell division inhibitor proteins, MinC/MinD, and the chromosome segregation protein, RacA. Little is known about the mechanism that localises DivIVA. Here we show that DivIVA binds to liposomes, and that the N terminus harbours the membrane targeting sequence. The purified protein can stimulate binding of RacA to membranes. In mutants with aberrant cell shapes, DivIVA accumulates where the cell membrane is most strongly curved. On the basis of electron microscopic studies and other data, we propose that this is due to molecular bridging of the curvature by DivIVA multimers. This model may explain why DivIVA localises at cell division sites. A Monte-Carlo simulation study showed that molecular bridging can be a general mechanism for binding of proteins to negatively curved membranes.

Show MeSH

Related in: MedlinePlus

Amino-acid alignment of DivIVA homologues (A) from the following: B. subtilis (B. sub.), S. aureus (S. aur.), S. pneumoniae (S. pneu.), M. tuberculosis (M. tub.) and S. coelicolor (S. coe.). Homologues and similar amino acids are boxed. The length of the C termini that extend beyond the B. subtilis DivIVA sequence is indicated. Presented above the sequence is the secondary structure prediction for B. subtilis DivIVA: c, coiled; h, helix. (B) Amphipathic helix prediction from the LOCATE program. The amino-acid positions are indicated and the Y axis shows the hydrophobic moments of the putative amphipathic helices.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2690451&req=5

f1: Amino-acid alignment of DivIVA homologues (A) from the following: B. subtilis (B. sub.), S. aureus (S. aur.), S. pneumoniae (S. pneu.), M. tuberculosis (M. tub.) and S. coelicolor (S. coe.). Homologues and similar amino acids are boxed. The length of the C termini that extend beyond the B. subtilis DivIVA sequence is indicated. Presented above the sequence is the secondary structure prediction for B. subtilis DivIVA: c, coiled; h, helix. (B) Amphipathic helix prediction from the LOCATE program. The amino-acid positions are indicated and the Y axis shows the hydrophobic moments of the putative amphipathic helices.

Mentions: DivIVA is conserved in Gram-positive bacteria. Secondary structure predictions show that the protein mainly forms α-helices (Figure 1A), and as DivIVA has some sequence similarity with tropomyosin, it is assumed that it forms coiled coils (Edwards et al, 2000). Biochemical and electron microscopic studies have shown that the purified protein forms multimers and assembles into large ordered lattices (Stahlberg et al, 2004). Despite the sequence conservation, the functional role of this protein varies between different bacterial species. In Bacillus subtilis, mutations in divIVA result in elongated cells that occasionally divide aberrantly near existing cell poles to produce minicells (Cha and Stewart, 1997). Fluorescence microscopy studies have shown that DivIVA is located at mid-cell during cell division and at matured cell poles, and that it is responsible for the polar localisation of the division inhibitor, MinC/MinD (Edwards and Errington, 1997; Marston et al, 1998). The first step in cell division in most bacteria is the polymerisation of the tubulin-like protein, FtsZ, into a ring-like structure (the Z-ring) onto which the cytokinesis apparatus assembles. In rod-shaped bacteria, MinC/MinD prevents polymerisation of FtsZ close to cell poles (Margolin, 2001; Hale and de Boer, 2002). When MinC/MinD is delocalised, as a consequence of inactive DivIVA, cell division is largely inhibited and, in addition, cells can divide aberrantly close to cell poles, producing small anucleate minicells. DivIVA also plays an important role during sporulation. Incorporation of DNA into the polar prespore compartment is achieved by anchoring one chromosome copy to the distal pole of the prespore compartment. One of the proteins involved in this process is RacA, and DivIVA is responsible for the polar localisation of RacA (Ben-Yehuda et al, 2003; Wu and Errington, 2003).


Localisation of DivIVA by targeting to negatively curved membranes.

Lenarcic R, Halbedel S, Visser L, Shaw M, Wu LJ, Errington J, Marenduzzo D, Hamoen LW - EMBO J. (2009)

Amino-acid alignment of DivIVA homologues (A) from the following: B. subtilis (B. sub.), S. aureus (S. aur.), S. pneumoniae (S. pneu.), M. tuberculosis (M. tub.) and S. coelicolor (S. coe.). Homologues and similar amino acids are boxed. The length of the C termini that extend beyond the B. subtilis DivIVA sequence is indicated. Presented above the sequence is the secondary structure prediction for B. subtilis DivIVA: c, coiled; h, helix. (B) Amphipathic helix prediction from the LOCATE program. The amino-acid positions are indicated and the Y axis shows the hydrophobic moments of the putative amphipathic helices.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2690451&req=5

f1: Amino-acid alignment of DivIVA homologues (A) from the following: B. subtilis (B. sub.), S. aureus (S. aur.), S. pneumoniae (S. pneu.), M. tuberculosis (M. tub.) and S. coelicolor (S. coe.). Homologues and similar amino acids are boxed. The length of the C termini that extend beyond the B. subtilis DivIVA sequence is indicated. Presented above the sequence is the secondary structure prediction for B. subtilis DivIVA: c, coiled; h, helix. (B) Amphipathic helix prediction from the LOCATE program. The amino-acid positions are indicated and the Y axis shows the hydrophobic moments of the putative amphipathic helices.
Mentions: DivIVA is conserved in Gram-positive bacteria. Secondary structure predictions show that the protein mainly forms α-helices (Figure 1A), and as DivIVA has some sequence similarity with tropomyosin, it is assumed that it forms coiled coils (Edwards et al, 2000). Biochemical and electron microscopic studies have shown that the purified protein forms multimers and assembles into large ordered lattices (Stahlberg et al, 2004). Despite the sequence conservation, the functional role of this protein varies between different bacterial species. In Bacillus subtilis, mutations in divIVA result in elongated cells that occasionally divide aberrantly near existing cell poles to produce minicells (Cha and Stewart, 1997). Fluorescence microscopy studies have shown that DivIVA is located at mid-cell during cell division and at matured cell poles, and that it is responsible for the polar localisation of the division inhibitor, MinC/MinD (Edwards and Errington, 1997; Marston et al, 1998). The first step in cell division in most bacteria is the polymerisation of the tubulin-like protein, FtsZ, into a ring-like structure (the Z-ring) onto which the cytokinesis apparatus assembles. In rod-shaped bacteria, MinC/MinD prevents polymerisation of FtsZ close to cell poles (Margolin, 2001; Hale and de Boer, 2002). When MinC/MinD is delocalised, as a consequence of inactive DivIVA, cell division is largely inhibited and, in addition, cells can divide aberrantly close to cell poles, producing small anucleate minicells. DivIVA also plays an important role during sporulation. Incorporation of DNA into the polar prespore compartment is achieved by anchoring one chromosome copy to the distal pole of the prespore compartment. One of the proteins involved in this process is RacA, and DivIVA is responsible for the polar localisation of RacA (Ben-Yehuda et al, 2003; Wu and Errington, 2003).

Bottom Line: In mutants with aberrant cell shapes, DivIVA accumulates where the cell membrane is most strongly curved.On the basis of electron microscopic studies and other data, we propose that this is due to molecular bridging of the curvature by DivIVA multimers.A Monte-Carlo simulation study showed that molecular bridging can be a general mechanism for binding of proteins to negatively curved membranes.

View Article: PubMed Central - PubMed

Affiliation: Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle upon Tyne, UK.

ABSTRACT
DivIVA is a conserved protein in Gram-positive bacteria and involved in various processes related to cell growth, cell division and spore formation. DivIVA is specifically targeted to cell division sites and cell poles. In Bacillus subtilis, DivIVA helps to localise other proteins, such as the conserved cell division inhibitor proteins, MinC/MinD, and the chromosome segregation protein, RacA. Little is known about the mechanism that localises DivIVA. Here we show that DivIVA binds to liposomes, and that the N terminus harbours the membrane targeting sequence. The purified protein can stimulate binding of RacA to membranes. In mutants with aberrant cell shapes, DivIVA accumulates where the cell membrane is most strongly curved. On the basis of electron microscopic studies and other data, we propose that this is due to molecular bridging of the curvature by DivIVA multimers. This model may explain why DivIVA localises at cell division sites. A Monte-Carlo simulation study showed that molecular bridging can be a general mechanism for binding of proteins to negatively curved membranes.

Show MeSH
Related in: MedlinePlus