Septum (cell biology)

A septum in cell biology is the new cell wall that forms between two daughter cells as a result of cell division.[1]

Septins in Saccharomyces cerevisiae (fluorescent micrograph)
• Green: septins (AgSEP7-GFP)
• Red: cell outline (phase contrast)
• Scale bar: 10 μm

In yeast, septins form a ring structure, to which other proteins are recruited.[2] In particular, chitinase 2 is required, an enzyme that synthesises chitin thereby building up the primary septum. A secondary septum of β-glucans and mannoproteins is then assembled using the enzyme 1,3-Beta-glucan synthase, and the primary septum degraded during cell separation. After degradation of the primary septum, a chitinous bud scar remains on both the mother and daughter cell. [2][3]

CompositionEdit

In Schizosaccharomyces pombe, the primary septum is composed of linear β(1,3)-D-glucan, β(1,6) branches, and α(1,3)-D-glucan.[4] The secondary septum in Schizosaccharomyces pombe is composed of β(1,6)-D-glucan, β(1,6) branches, and α(1,3)-D-glucan.[4] The synthesis of linear β(1,3)-D-glucan for the primary septum is done by the enzyme β(1,3)-D-glucan synthase and regulated by a Rho GTPase.[4] Ags1/Mok1 enzyme is responsible for the synthesis of α(1,3)-D-glucan in the primary septum and secondary septum. [4]

ReferencesEdit

  1. ^ O'Connor C (2008). "Cell Division: Stages of Mitosis". Nature Education. 1 (1): 188.
  2. ^ a b Cabib E, Roh DH, Schmidt M, Crotti LB, Varma A (June 2001). "The yeast cell wall and septum as paradigms of cell growth and morphogenesis". The Journal of Biological Chemistry. 276 (23): 19679–82. doi:10.1074/jbc.R000031200. PMID 11309404.
  3. ^ Lesage G, Bussey H (June 2006). "Cell wall assembly in Saccharomyces cerevisiae". Microbiology and Molecular Biology Reviews. 70 (2): 317–43. doi:10.1128/MMBR.00038-05. PMC 1489534. PMID 16760306.
  4. ^ a b c d García Cortés JC, Ramos M, Osumi M, Pérez P, Ribas JC (September 2016). "The Cell Biology of Fission Yeast Septation". Microbiology and Molecular Biology Reviews. 80 (3): 779–91. doi:10.1128/MMBR.00013-16. PMC 4981666. PMID 27466282.