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Continuous periplasm in a filamentous, heterocyst‐forming cyanobacterium
Author(s) -
Mariscal Vicente,
Herrero Antonia,
Flores Enrique
Publication year - 2007
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2007.05856.x
Subject(s) - heterocyst , periplasmic space , biology , green fluorescent protein , cytoplasm , microbiology and biotechnology , anabaena , peptidoglycan , bacterial outer membrane , protein filament , cyanobacteria , cell wall , gene , biochemistry , bacteria , genetics , escherichia coli
Summary The cyanobacteria bear a Gram‐negative type of cell wall that includes a peptidoglycan layer and an outer membrane outside of the cytoplasmic membrane. In filamentous cyanobacteria, the outer membrane appears to be continuous along the filament of cells. In the heterocyst‐forming cyanobacteria, two cell types contribute specialized functions for growth: vegetative cells provide reduced carbon to heterocysts, which provide N 2 ‐derived fixed nitrogen to vegetative cells. The promoter of the patS gene, which is active specifically in developing proheterocysts and heterocysts of Anabaena sp. PCC 7120, was used to direct the expression of altered versions of the gfp gene. An engineered green fluorescent protein (GFP) that was exported to the periplasm of the proheterocysts through the twin‐arginine translocation system was observed also in the periphery of neighbouring vegetative cells. However, if the GFP was anchored to the cytoplasmic membrane, it was observed in the periphery of the producing proheterocysts or heterocysts but not in adjacent vegetative cells. These results show that there is no cytoplasmic membrane continuity between heterocysts and vegetative cells and that the GFP protein can move along the filament in the periplasm, which is functionally continuous and so provides a conduit that can be used for chemical communication between cells.