CcbP, a calcium-binding protein from Anabaena sp. PCC 7120, provides evidence that calcium ions regulate heterocyst differentiation
AUTOR(ES)
Zhao, Yinhong
FONTE
National Academy of Sciences
RESUMO
Although it is known that calcium is a very important messenger involved in many eukaryotic cellular processes, much less is known about calcium's role in bacteria. CcbP, a Ca2+-binding protein, was isolated from the heterocystous cyanobacterium Anabaena sp. PCC 7120, and the ccbP gene was cloned and inactivated. In the absence of combined nitrogen, inactivation of ccbP resulted in multiple contiguous heterocysts, whereas overexpression of ccbP suppressed heterocyst formation. Calmodulin, which is not present in Anabaena species, could also suppress heterocyst formation in both Anabaena sp. PCC 7120 and Anabaena variabilis. HetR induction upon nitrogen step-down was slow in the strain overexpressing ccbP. The Ca2+ reporter protein obelin was used to show that mature heterocysts had a high intracellular free Ca2+concentration {[Ca2+]i}, and immunoblotting showed that CcbP was absent from heterocysts. A regular pattern of cells with higher [Ca2+]i was established during heterocyst differentiation before the appearance of proheterocysts. A rapid increase of [Ca2+]i could be detected 4 h after the removal of combined nitrogen, and this increase was suppressed by excessive CcbP. These results suggest that Ca2+ ions play very important roles in hetR induction and heterocyst differentiation.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=556313Documentos Relacionados
- Different functions of HetR, a master regulator of heterocyst differentiation in Anabaena sp. PCC 7120, can be separated by mutation
- Anabaena sp. Strain PCC 7120 hetY Gene Influences Heterocyst Development
- Developmental Regulation of the Cell Division Protein FtsZ in Anabaena sp. Strain PCC 7120, a Cyanobacterium Capable of Terminal Differentiation
- Nonmetabolizable analogue of 2-oxoglutarate elicits heterocyst differentiation under repressive conditions in Anabaena sp. PCC 7120
- Nitrate assimilation gene cluster from the heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120.