2024-03-28T19:50:54Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/1117472021-12-28T15:38:32Zcom_10261_80com_10261_1col_10261_333
HetR-dependent and -independent expression of heterocyst-related genes in an Anabaena strain overproducing the NtcA transcription factor
Olmedo-Verd, E.
Flores, Enrique
Herrero, Antonia
Muro-Pastor, Alicia M.
Heterocyst development in the cyanobacterium Anabaena sp. strain PCC 7120 depends on both the global nitrogen control transcription factor NtcA and the cell differentiation regulatory protein HetR, with expression of ntcA and hetR being dependent on each other. In this study we constructed strains that constitutively express the ntcA gene leading to high levels of NtcA protein irrespective of the nitrogen source, and we analyzed the elects of such NtcA levels on heterocyst diferentiation. In the NtcA-overproducing strain, heterocyst differentiation, induction of NtcA-dependent heterocyst development genes or operons such as devBCA or the cox2 operon, and NtcA-dependent excision of the 11-kb nifD-intervening element only took place under nitrogen deficiency. Although functional heterocysts were produced in response to nitrogen step-down, the NtcA over-producing strain could not grow diazotrophically. Overexpression of ntcA in a hetR background promoted expression of devBCA in response to ammonium withdrawal and excision of the 11-kb element even in the presence of combined nitrogen. Our results show that some NtcA-dependent heterocyst-related genes can be expressed independently of HetR. Copyright © 2005, American Society for Microbiology. All Rights Reserved.
2015-03-04T09:06:08Z
2015-03-04T09:06:08Z
2005
2015-03-04T09:06:09Z
artículo
Journal of Bacteriology 187: 1985- 1991 (2005)
http://hdl.handle.net/10261/111747
10.1128/JB.187.6.1985-1991.2005
15743946
eng
openAccess
American Society for Microbiology