2024-03-29T06:23:52Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/1473562019-11-13T11:10:20Zcom_10261_80com_10261_1col_10261_333
Molecular Diffusion through Cyanobacterial Septal Junctions
Nieves-Morión, Mercedes
Mullineaux, Conrad W.
Flores, Enrique
Heterocyst-forming cyanobacteria grow as filaments in which intercellular
molecular exchange takes place. During the differentiation of N2-fixing heterocysts,
regulators are transferred between cells. In the diazotrophic filament, vegetative
cells that fix CO2 through oxygenic photosynthesis provide the heterocysts with
reduced carbon and heterocysts provide the vegetative cells with fixed nitrogen. Intercellular
molecular transfer has been traced with fluorescent markers, including
calcein, 5-carboxyfluorescein, and the sucrose analogue esculin, which are observed
to move down their concentration gradient. In this work, we used fluorescence recovery
after photobleaching (FRAP) assays in the model heterocyst-forming cyanobacterium
Anabaena sp. strain PCC 7120 to measure the temperature dependence
of intercellular transfer of fluorescent markers. We find that the transfer rate constants
are directly proportional to the absolute temperature. This indicates that the
“septal junctions” (formerly known as “microplasmodesmata”) linking the cells in the
filament allow molecular exchange by simple diffusion, without any activated intermediate
state. This constitutes a novel mechanism for molecular transfer across the
bacterial cytoplasmic membrane, in addition to previously characterized mechanisms
for active transport and facilitated diffusion. Cyanobacterial septal junctions are functionally
analogous to the gap junctions of metazoans
2017-03-27T08:06:38Z
2017-03-27T08:06:38Z
2017
artículo
mBio, 8: e01756-16. (2017)
http://hdl.handle.net/10261/147356
10.1128/ mBio.01756-16.
eng
Publisher's version
https://doi.org/10.1128/ mBio.01756-16.
Sí
Creative Commons CC-BY 4.0
openAccess
American Society for Microbiology