Genetic analysis of response regulator activation in bacterial chemotaxis suggests an intermolecular mechanism.
Response regulator proteins of two-component systems are usually activated by phosphorylation. The phosphorylated response regulator protein CheY-P mediates the chemotaxis response in Escherichia coli. We performed random mutagenesis and selected CheY mutants that are constitutively active in the absence of phosphorylation. Although a single amino acid substitution can lead to constitutive activation, no single DNA base change can effect such a transition. Numerous different sets of mutations that activate in synergy were selected in several different combinations. These mutations were all located on the side of CheY defined by alpha4, beta5, alpha5, and alpha1. Our findings argue against the two-state hypothesis for response regulator activation. We propose an alternative intermolecular mechanism that involves a dynamic interplay between response regulators and their effector targets.
Da Re
Sandra
S
Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544, USA.
Tolstykh
Tatiana
T
Wolanin
Peter M
PM
Stock
Jeffry B
JB
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001426:Bacterial Proteins; D002633:Chemotaxis / Q000502:physiology; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D000072236:Methyl-Accepting Chemotaxis Proteins; D008958:Models, Molecular; D016296:Mutagenesis; D009154:Mutation; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D015398:Signal Transduction / Q000502:physiology
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; C000607606:cheY protein, E coli