Solution conformation of HrpZ2 protein from Pseudomonas syringae

Arpita Goswami.

SASDS66 – Solution conformation of Harpin HrpZ2 protein from Pseudomonas syringae, a plant pathogen

Harpin Z2
MWexperimental 39 kDa
MWexpected 37 kDa
VPorod 64 nm3
log I(s) 1.76×100 1.76×10-1 1.76×10-2 1.76×10-3
Harpin Z2 small angle scattering data  s, nm-1
ln I(s)
Harpin Z2 Guinier plot ln 1.76×100 Rg: 3.1 nm 0 (3.1 nm)-2 s2
(sRg)2I(s)/I(0)
Harpin Z2 Kratky plot 1.104 0 3 sRg
Dmax: 8.8 nm

Data validation


Fits and models


log I(s)
 s, nm-1
Harpin Z2 CORAL model

SAXS data from solutions of Harpin HrpZ2 protein in 10 mM MES, 100 mM NaF, pH 6.2 were collected using a Rigaku BioSAXS 2000 instrument at the Centre for Cellular & Molecular Biology (CCMB; Hyderabad, India) equipped with a Rigaku HyPix-3000 hybrid pixel array detector at a sample-detector distance of 0.5 m and at a wavelength of λ = 0.154178 nm (I(s) vs s, where s = 4πsinθ/λ, and 2θ is the scattering angle). Solute concentrations ranging between 1 and 4 mg/ml were measured at 22°C. Six successive 300 second frames were collected. The data were normalized to the intensity of the transmitted beam and radially averaged; the scattering of the solvent-blank was subtracted.

Different concentrations of protein was used: 1, 2 and 4 mg/ml. Blank buffer (10 mM MES, pH 6.2, 100 mM NaF) was run along with. Best result came with 1 mg/ml which showed the above values for a monomer protein. The spheroidal shape of the protein was oblate (flat). The molecular weight = 38.8 kD calculated from Vc (volume of correlation) method was most close to theoretical monomeric molecular weight (36.75 kD) of the N-terminal his tagged protein as compared to other methods. Note: For 2 mg/ml concentration (not shown here), tendency of protein to form oligomer can be seen due to rise in Dmax (11.4 nm) from 8.77 nm (for 1 mg/ml concentration).

Harpin Z2 (HrpZ2)
Mol. type   Protein
Organism   Pseudomonas syringae strain MTCC 11950
Olig. state   Monomer
Mon. MW   36.8 kDa
Sequence   FASTA