The structure of the KinA-Sda complex suggests an allosteric mechanism of histidine kinase inhibition.

Whitten AE, Jacques DA, Hammouda B, Hanley T, King GF, Guss JM, Trewhella J, Langley DB, J Mol Biol 368(2):407-20 (2007) Europe PMC

SASDHY3 – KinA-Sda complex

Sporulation kinase A
Sporulation inhibitor sda
MWI(0) 75 kDa
MWexpected 62 kDa
VPorod 85 nm3
log I(s) 8.05×102 8.05×101 8.05×100 8.05×10-1
Sporulation kinase A Sporulation inhibitor sda small angle scattering data  s, nm-1
ln I(s)
Sporulation kinase A Sporulation inhibitor sda Guinier plot ln 8.05×102 Rg: 2.9 nm 0 (2.9 nm)-2 s2
(sRg)2I(s)/I(0)
Sporulation kinase A Sporulation inhibitor sda Kratky plot 1.104 0 3 sRg
p(r)
Sporulation kinase A Sporulation inhibitor sda pair distance distribution function Rg: 2.9 nm 0 Dmax: 8 nm

Data validation


Fits and models


log I(s)
 s, nm-1
Sporulation kinase A Sporulation inhibitor sda SASREF model

X-ray scattering data from the from the autokinase domain of the histidine kinase KinA complexed with the checkpoint inhibitor Sda in 50 mM Tris-HCl 200 mM NaCl 150 mM imidazole pH 8.5 were collected on a Bruker Nanostar instrument at the Bragg Institute (Australian Nuclear Science and Technology Organisation, Lucas Heights, Australia) using a HiStar 2D detector (I(s) vs s, where s = 4π sin θ/λ and 2θ is the scattering angle; λ=0.15406 nm). Approximately 15 µL of an 11.9 mg/ml protein solution was loaded into a quartz capillary mounted in a stainless steel holder. A single 3600s second frame was collected, and the buffer was collected in an analogous fashion. The data were radially averaged, and the scattering of the solvent-blank was subtracted. The data are on an arbitrary scale, and the mass of the protein was determined using a lysozyme secondary standard at a concentration of 17.5 mg/ml. Small-angle neutron scattering data with contrast variation were also collected on the NG3 instrument at the NIST Centre for Neutron Research at a solute concentration of ~11.9 mg/ml. A rigid-body model was co-refined against the SAXS and SANS data using using SASREF (v 7e), and this model is shown, together with the X-ray data and corresponding fit. Details of the SANS data collection, fits, and additional analysis are contained in a downloadable zip archive.

Sporulation kinase A (KinA)
Mol. type   Protein
Organism   Bacillus subtilis
Olig. state   Dimer
Mon. MW   25.4 kDa
 
UniProt   P16497 (383-606)
Sequence   FASTA
 
Sporulation inhibitor sda (Sda)
Mol. type   Protein
Organism   Bacillus subtilis
Olig. state   Dimer
Mon. MW   5.6 kDa
 
UniProt   Q7WY62 (7-52)
Sequence   FASTA