Insights into the mechanism of activation of the phosphorylation-independent response regulator NblR. Role of residues Cys69 and Cys96.
Cyanobacteria respond to environmental stress conditions by adjusting their photosynthesis machinery. In Synechococcus sp. PCC 7942, phycobilisome degradation and other acclimation responses after nutrient or high light stress require activation by the phosphorylation-independent response regulator NblR. Structural modelling of its receiver domain suggested a role for Cys69 and Cys96 on activation of NblR. Here, we investigate this hypothesis by engineering Cys to Ala substitutions. In vivo and in vitro analyses indicated that mutations Cys69Ala and/or Cys96Ala have a minor impact on NblR function, structure, size, or oligomerization state of the protein, and that Cys69 and Cys96 do not seem to form disulphide bridges. Our results argue against the predicted involvement of Cys69 and Cys96 on NblR activation by redox sensing.
División de Genética, Universidad de Alicante, Alicante, Spain.
Javier
J
Espinosa
Maria-Luisa
ML
López-Redondo
Laura
L
Miguel-Romero
José L
JL
Neira
Alberto
A
Marina
Asunción
A
Contreras
D000409:Alanine / Q000235:genetics / Q000502:physiology; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics / Q000502:physiology; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D003545:Cysteine / Q000235:genetics / Q000502:physiology; D015964:Gene Expression Regulation, Bacterial; D008027:Light; D010084:Oxidation-Reduction; D010766:Phosphorylation; D010788:Photosynthesis / Q000235:genetics / Q000502:physiology; D045524:Phycobilisomes / Q000235:genetics / Q000502:physiology; D011487:Protein Conformation; D016415:Sequence Alignment; D013312:Stress, Physiological; D046940:Synechococcus / Q000235:genetics / Q000502:physiology; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000502:physiology
D001426:Bacterial Proteins; C114424:NblR protein, Synechococcus sp.; D045524:Phycobilisomes; D014157:Transcription Factors; D003545:Cysteine; D000409:Alanine