Branched signal wiring of an essential bacterial cell-cycle phosphotransfer protein.
Vital to bacterial survival is the faithful propagation of cellular signals, and in Caulobacter crescentus, ChpT is an essential mediator within the cell-cycle circuit. ChpT functions as a histidine-containing phosphotransfer protein (HPt) that shuttles a phosphoryl group from the receiver domain of CckA, the upstream hybrid histidine kinase (HK), to one of two downstream response regulators (CtrA or CpdR) that controls cell-cycle progression. To understand how ChpT interacts with multiple signaling partners, we solved the crystal structure of ChpT at 2.3 Å resolution. ChpT adopts a pseudo-HK architecture but does not bind ATP. We identified two point mutation classes affecting phosphotransfer and cell morphology: one that globally impairs ChpT phosphotransfer, and a second that mediates partner selection. Importantly, a small set of conserved ChpT residues promotes signaling crosstalk and contributes to the branched signaling that activates the master regulator CtrA while inactivating the CtrA degradation signal, CpdR.
Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
Jimmy A
JA
Blair
Qingping
Q
Xu
W Seth
WS
Childers
Irimpan I
II
Mathews
Justin W
JW
Kern
Michael
M
Eckart
Ashley M
AM
Deacon
Lucy
L
Shapiro
D000255:Adenosine Triphosphate / Q000737:chemistry; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D016935:Caulobacter crescentus / Q000201:enzymology* / Q000254:growth & development; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D006868:Hydrolysis; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010766:Phosphorylation; D017354:Point Mutation; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D017433:Protein Structure, Secondary; D015398:Signal Transduction; D014166:Transferases / Q000737:chemistry* / Q000235:genetics / Q000502:physiology
D001426:Bacterial Proteins; D000255:Adenosine Triphosphate; D014166:Transferases