Glutamate at the phosphorylation site of response regulator CtrA provides essential activities without increasing DNA binding.
The essential response regulator CtrA controls the Caulobacter crescentus cell cycle and phosphorylated CtrA approximately P preferentially binds target DNA in vitro. The CtrA aspartate to glutamate (D51E) mutation mimics phosphorylated CtrA approximately P in vivo and rescues non-viable C.crescentus cells. However, we observe that the CtrA D51E and the unphosphorylated CtrA wild-type proteins have identical DNA affinities and produce identical DNase I protection footprints inside the C.crescentus replication origin. There fore, D51E promotes essential CtrA activities separate from increased DNA binding. Accordingly, we argue that CtrA protein recruitment to target DNA is not sufficient to regulate cell cycle progression.
Siam
Rania
R
Department of Microbiology and Immunology, McGill University, 3775 University Street, Montreal, Quebec H3A 2B4, Canada.
Marczynski
Gregory T
GT
D019943:Amino Acid Substitution; D001426:Bacterial Proteins; D001665:Binding Sites / Q000235:genetics; D001667:Binding, Competitive; D016935:Caulobacter crescentus / Q000235:genetics / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D005838:Genotype; D018698:Glutamic Acid / Q000235:genetics*; D007700:Kinetics; D010766:Phosphorylation; D011485:Protein Binding; D018741:Replication Origin / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; C097706:CtrA protein, Caulobacter; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D014157:Transcription Factors; D018698:Glutamic Acid