| Structural highlights
Function
[SP2Q_BACSU] Involved in forespore engulfment and required for anchoring membrane proteins on the forespore side of the septal membrane. Forms a channel with SpoIIIAH that is open on the forespore end and closed (or gated) on the mother cell end. This allows sigma-E-directed gene expression in the mother-cell compartment of the sporangium to trigger the activation of sigma-G forespore-specific gene expression by a pathway of intercellular signaling.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [SP3AH_BACSU] Involved in forespore engulfment. Forms a channel with SpoIIIAH that is open on the forespore end and closed (or gated) on the mother cell end. This allows sigma-E-directed gene expression in the mother-cell compartment of the sporangium to trigger the activation of sigma-G forespore-specific gene expression by a pathway of intercellular signaling.[11] [12] [13] [14] [15] [16] [17]
Publication Abstract from PubMed
Following asymmetric cell division during spore formation in Bacillus subtilis, a forespore expressed membrane protein SpoIIQ, interacts across an intercellular space with a mother cell-expressed membrane protein, SpoIIIAH. Their interaction can serve as a molecular "ratchet" contributing to the migration of the mother cell membrane around that of the forespore in a phagocytosis-like process termed engulfment. Upon completion of engulfment, SpoIIQ and SpoIIIAH are integral components of a recently proposed intercellular channel allowing passage from the mother cell into the forespore of factors required for late gene expression in this compartment. Here we show that the extracellular domains of SpoIIQ and SpoIIIAH form a heterodimeric complex in solution. The crystal structure of this complex reveals that SpoIIQ has a LytM-like zinc-metalloprotease fold but with an incomplete zinc coordination sphere and no metal. SpoIIIAH has an alpha-helical subdomain and a protruding beta-sheet subdomain, which mediates interactions with SpoIIQ. SpoIIIAH has sequence and structural homology to EscJ, a type III secretion system protein that forms a 24-fold symmetric ring. Superposition of the structures of SpoIIIAH and EscJ reveals that the SpoIIIAH protomer overlaps with two adjacent protomers of EscJ, allowing us to generate a dodecameric SpoIIIAH ring by using structural homology. Following this superposition, the SpoIIQ chains also form a closed dodecameric ring abutting the SpoIIIAH ring, producing an assembly surrounding a 60 A channel. The dimensions and organization of the proposed complex suggest it is a plausible model for the extracellular component of a gap junction-like intercellular channel.
Structure of components of an intercellular channel complex in sporulating Bacillus subtilis.,Levdikov VM, Blagova EV, McFeat A, Fogg MJ, Wilson KS, Wilkinson AJ Proc Natl Acad Sci U S A. 2012 Apr 3;109(14):5441-5. Epub 2012 Mar 19. PMID:22431604[18]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Londono-Vallejo JA, Frehel C, Stragier P. SpoIIQ, a forespore-expressed gene required for engulfment in Bacillus subtilis. Mol Microbiol. 1997 Apr;24(1):29-39. PMID:9140963
- ↑ Sun YL, Sharp MD, Pogliano K. A dispensable role for forespore-specific gene expression in engulfment of the forespore during sporulation of Bacillus subtilis. J Bacteriol. 2000 May;182(10):2919-27. PMID:10781563
- ↑ Dworkin J, Losick R. Developmental commitment in a bacterium. Cell. 2005 May 6;121(3):401-9. PMID:15882622 doi:http://dx.doi.org/10.1016/j.cell.2005.02.032
- ↑ Doan T, Marquis KA, Rudner DZ. Subcellular localization of a sporulation membrane protein is achieved through a network of interactions along and across the septum. Mol Microbiol. 2005 Mar;55(6):1767-81. PMID:15752199 doi:http://dx.doi.org/10.1111/j.1365-2958.2005.04501.x
- ↑ Jiang X, Rubio A, Chiba S, Pogliano K. Engulfment-regulated proteolysis of SpoIIQ: evidence that dual checkpoints control sigma activity. Mol Microbiol. 2005 Oct;58(1):102-15. PMID:16164552 doi:http://dx.doi.org/MMI4811
- ↑ Broder DH, Pogliano K. Forespore engulfment mediated by a ratchet-like mechanism. Cell. 2006 Sep 8;126(5):917-28. PMID:16959571 doi:http://dx.doi.org/10.1016/j.cell.2006.06.053
- ↑ Aung S, Shum J, Abanes-De Mello A, Broder DH, Fredlund-Gutierrez J, Chiba S, Pogliano K. Dual localization pathways for the engulfment proteins during Bacillus subtilis sporulation. Mol Microbiol. 2007 Sep;65(6):1534-46. PMID:17824930 doi:http://dx.doi.org/MMI5887
- ↑ Campo N, Marquis KA, Rudner DZ. SpoIIQ anchors membrane proteins on both sides of the sporulation septum in Bacillus subtilis. J Biol Chem. 2008 Feb 22;283(8):4975-82. Epub 2007 Dec 11. PMID:18077456 doi:http://dx.doi.org/10.1074/jbc.M708024200
- ↑ Camp AH, Losick R. A novel pathway of intercellular signalling in Bacillus subtilis involves a protein with similarity to a component of type III secretion channels. Mol Microbiol. 2008 Jul;69(2):402-17. doi: 10.1111/j.1365-2958.2008.06289.x. PMID:18485064 doi:http://dx.doi.org/10.1111/j.1365-2958.2008.06289.x
- ↑ Meisner J, Wang X, Serrano M, Henriques AO, Moran CP Jr. A channel connecting the mother cell and forespore during bacterial endospore formation. Proc Natl Acad Sci U S A. 2008 Sep 30;105(39):15100-5. doi:, 10.1073/pnas.0806301105. Epub 2008 Sep 23. PMID:18812514 doi:http://dx.doi.org/10.1073/pnas.0806301105
- ↑ Blaylock B, Jiang X, Rubio A, Moran CP Jr, Pogliano K. Zipper-like interaction between proteins in adjacent daughter cells mediates protein localization. Genes Dev. 2004 Dec 1;18(23):2916-28. PMID:15574594 doi:http://dx.doi.org/10.1101/gad.1252704
- ↑ Doan T, Marquis KA, Rudner DZ. Subcellular localization of a sporulation membrane protein is achieved through a network of interactions along and across the septum. Mol Microbiol. 2005 Mar;55(6):1767-81. PMID:15752199 doi:http://dx.doi.org/10.1111/j.1365-2958.2005.04501.x
- ↑ Jiang X, Rubio A, Chiba S, Pogliano K. Engulfment-regulated proteolysis of SpoIIQ: evidence that dual checkpoints control sigma activity. Mol Microbiol. 2005 Oct;58(1):102-15. PMID:16164552 doi:http://dx.doi.org/MMI4811
- ↑ Broder DH, Pogliano K. Forespore engulfment mediated by a ratchet-like mechanism. Cell. 2006 Sep 8;126(5):917-28. PMID:16959571 doi:http://dx.doi.org/10.1016/j.cell.2006.06.053
- ↑ Aung S, Shum J, Abanes-De Mello A, Broder DH, Fredlund-Gutierrez J, Chiba S, Pogliano K. Dual localization pathways for the engulfment proteins during Bacillus subtilis sporulation. Mol Microbiol. 2007 Sep;65(6):1534-46. PMID:17824930 doi:http://dx.doi.org/MMI5887
- ↑ Camp AH, Losick R. A novel pathway of intercellular signalling in Bacillus subtilis involves a protein with similarity to a component of type III secretion channels. Mol Microbiol. 2008 Jul;69(2):402-17. doi: 10.1111/j.1365-2958.2008.06289.x. PMID:18485064 doi:http://dx.doi.org/10.1111/j.1365-2958.2008.06289.x
- ↑ Meisner J, Wang X, Serrano M, Henriques AO, Moran CP Jr. A channel connecting the mother cell and forespore during bacterial endospore formation. Proc Natl Acad Sci U S A. 2008 Sep 30;105(39):15100-5. doi:, 10.1073/pnas.0806301105. Epub 2008 Sep 23. PMID:18812514 doi:http://dx.doi.org/10.1073/pnas.0806301105
- ↑ Levdikov VM, Blagova EV, McFeat A, Fogg MJ, Wilson KS, Wilkinson AJ. Structure of components of an intercellular channel complex in sporulating Bacillus subtilis. Proc Natl Acad Sci U S A. 2012 Apr 3;109(14):5441-5. Epub 2012 Mar 19. PMID:22431604 doi:10.1073/pnas.1120087109
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