Subcellular Localization and Clues for the Function of the HetN Factor Influencing Heterocyst Distribution in Anabaena sp. Strain PCC 7120

摘要: ABSTRACT In the filamentous cyanobacterium Anabaena sp. strain PCC 7120, heterocysts are formed in absence of combined nitrogen, following a specific distribution pattern along filament. The PatS and HetN factors contribute to heterocyst by inhibiting formation consecutive heterocysts. Thus, inactivation any these produces multiple contiguous (Mch) phenotype. Upon N stepdown, protein with its C terminus fused superfolder version green fluorescent (sf-GFP) or GFP-mut2 was observed, localized first throughout whole area differentiating cells later specifically on peripheries polar regions mature heterocysts, coinciding location thylakoids. Polar localization required an N-terminal stretch comprising residues 2 27 that may represent unconventional signal peptide. strains expressing lacking this fragment from mutant gene placed at native hetN locus exhibited mild Mch agreement previous results, deletion internal ERGSGR sequence, which is identical C-terminal sequence PatS, also led subcellular fluorescence resulting fusion GFP suggests full present cells. Furthermore, more conserved among cyanobacteria than sequence. These observations suggest anchored thylakoid membranes serve function besides generating regulatory (ERGSGR)