Solution conformation of HrpZ2 protein from Pseudomonas syringae

Arpita Goswami.

SASDS37 – Oligomerization initiating solution conformation of Harpin HrpZ2 protein from Pseudomonas syringae, a plant pathogen

Harpin Z2
MWexperimental 45 kDa
MWexpected 37 kDa
VPorod 70 nm3
log I(s) 3.17×100 3.17×10-1 3.17×10-2 3.17×10-3
Harpin Z2 small angle scattering data  s, nm-1
ln I(s)
Harpin Z2 Guinier plot ln 3.18×100 Rg: 3.2 nm 0 (3.2 nm)-2 s2
(sRg)2I(s)/I(0)
Harpin Z2 Kratky plot 1.104 0 √3 sRg
p(r)
Harpin Z2 pair distance distribution function Rg: 3.3 nm 0 Dmax: 11.4 nm

Data validation

Fits and models

log I(s)
 s, nm-1
Harpin Z2 CORAL model
SAXS data from solutions of the oligomerization initiating solution conformation of Harpin HrpZ2 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). One solute concentration of 2.00 mg/ml was 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. This results displayed above are derived from the 2 mg/ml sample. The spheroidal shape of the protein was prolate (extended) at this concentration. This is different from the behavior of the protein as oblate (flat) molecule in monomer concentration (1 mg/ml). The molecular weight = 44.9 kD calculated from Vc (volume of correlation) method was more than the theoretical monomer molecular weight (36.75 kD) of the N-terminal his tagged protein. For 2 mg/ml concentration, the tendency of protein to form oligomers can be seen due to rise in Dmax (11.4 nm) from 8.77 nm (for 1 mg/ml concentration used in monomer).

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