heterocyst

Edge evidence

• cell differentiation enables heterocyst RO:0002327

  Cyanobacterial cell differentiation realizes the thick-walled heterocyst.

  • DOI:10.1093/femsre/fuw029 Herrero et al. describe heterocysts within the multicellular filament of heterocyst-forming cyanobacteria.
• heterocyst causes microoxic intracellular environment biolink:causes

  The thick heterocyst wall and altered metabolism produce a microoxic interior.

  • DOI:10.1101/cshperspect.a000315 Kumar et al. describe heterocysts as differentiated cells whose structure accommodates oxygen-sensitive N2 fixation.
• microoxic intracellular environment enables nitrogen fixation RO:0002327

  The microoxic interior protects nitrogenase, enabling N2 fixation.

  • DOI:10.1101/cshperspect.a000315 Kumar et al. link heterocyst microoxia to oxygen-sensitive N2 fixation.
• HetR transcriptional regulator positively regulates heterocyst differentiation

  HetR is the master positive regulator of heterocyst development.

  • DOI:10.1371/journal.pone.0289761 "hetR, the master regulator of heterocyst development".
• FurC / PerR binds promoter of hetR promoter

  FurC binds distal and proximal regions of the hetR promoter.

  • DOI:10.1371/journal.pone.0289761 EMSA detected FurC binding to distal (S1) and proximal (S3) regions of the hetR promoter.
• heterocyst glycolipid layer (HGL) reduces diffusion of oxygen

  The inner glycolipid layer reduces O2 gas diffusion into the heterocyst.

  • DOI:10.1101/2023.10.04.560878 "the inner heterocyst-specific glycolipid layer (HGL) reduces gas diffusion (including O2)".
• heterocyst envelope polysaccharide layer (HEP) provides mechanical support to heterocyst glycolipid layer (HGL)

  The outer polysaccharide layer mechanically supports the glycolipid layer.

  • DOI:10.1101/2023.10.04.560878 "the outer heterocyst envelope polysaccharide layer (HEP) provides mechanical support to the HGL".
• heterocyst envelope (Hgl/Hep) enables microoxic intracellular environment RO:0002327

  The Hgl/Hep envelope contributes to creating the microoxic heterocyst interior.

  • DOI:10.1093/pcp/pcae011 "These oxygen protection mechanisms create hypoxic environments in the heterocysts so that nitrogenase can operate".
• PatS peptide negatively regulates heterocyst differentiation

  PatS inactivation yields a multiple-contiguous-heterocyst phenotype, indicating negative regulation of differentiation/spacing.

  • DOI:10.1101/2023.10.04.560878 "inactivation of one of the genes patS and hetN" caused the Mch (multiple contiguous heterocyst) phenotype.
• HetN regulator negatively regulates heterocyst differentiation

  HetN inactivation yields multiple contiguous heterocysts, indicating negative regulation of differentiation/spacing.

  • DOI:10.1101/2023.10.04.560878 "inactivation of one of the genes patS and hetN" caused the Mch phenotype.