title: Crosstalk regulation among group 2-sigma factors in Synechocystis PCC6803.
abstract: BACKGROUND
  The cyanobacterium Synechocystis PCC6803 contains one group 1 (sigA) and four group 2 (sigB, sigC, sigD and sigE) sigma factors. The activity of these multiple sigma factors determines the transcriptional program of this bacterium. We wanted to study the role of the group 2 sigma factors in Synechocystis. We have therefore constructed mutants of each of the group 2 sigma factors and investigated their crosstalk.
  
  
  RESULTS
  We used quantitative RT-PCR analysis to measure the relative abundance of the sig mRNAs in the four sigma mutants. Our data indicate that a network of mutual transcriptional regulation links the expression of the sigma genes. Accordingly, an environmental stress acting on only one of the sigma factors will indirectly modify the expression of most of the other sigma factors. This was confirmed by the transcriptional analysis of the sig mRNAs as a function of nitrogen starvation.
  
  
  CONCLUSIONS
  Taken together, our observations suggest that the crosstalk regulation between all group 1 and group 2 genes could be important for the adaptation of the bacterium to different environmental and physiological conditions.
authors.affiliation: Laboratoire Adaptation et Pathogénie des Microorganismes, Université Joseph Fourier Bâtiment Jean Roget, Faculté Médecine-Pharmacie, Domaine de la Merci, 38700 La Tronche, France. sylvain.lemeille@ujf-grenoble.fr
authors.forename: Sylvain
authors.initials: S
authors.lastname: Lemeille
authors.forename: Johannes
authors.initials: J
authors.lastname: Geiselmann
authors.forename: Amel
authors.initials: A
authors.lastname: Latifi
mesh_terms: D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D046939:Synechocystis / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D012808:Sigma Factor