Extended Data Figure 5: TssA oligomerization and SAXS and EM structural models.
From: Priming and polymerization of a bacterial contractile tail structure
a, 10 μg of purified TssA were analysed by SDS–PAGE and Coomassie blue staining. The molecular weight markers (in kDa) are indicated on the left, and TssA and its theoretical size are indicated on the right. b, Superose 6 10/300 gel filtration profile of purified TssA (black line) and protein markers of known size (coloured lines). c, MALS/QELS/UV/RI analysis of purified TssA. The molecular mass of the TssA complex is indicated. d–j, Low-resolution SAXS model of TssA. d, Experimental scattering data calculated from an ab initio model of TssA. The square root χ value of the ‘best representative’ model is indicated. e, Representation of the Guinier plot calculated from the experimental curve. f, Pair distance distribution. g, Kratky plot representative of a multi-domain protein with flexible linkers. h–j, SAXS envelope of the ‘best representative’ model of TssA, with top (h), side (i) and tilted (j) views. The scale bar is 100 Å. k–r, Low-resolution EM model of TssA. k, Representative micrograph of the data set used for image processing. White circles indicate isolated TssA dodecamers. l. Representative selected TssA particles. m, n, Gallery of representative top (m) and side (n) class averages generated after reference-free 2D classification using Relion39. o, Fourier shell correlation (FSC) curve of the TssA reconstruction. The gold standard FSC curve was calculated in Relion39 using the masked reconstruction of TssA. p–r, Top (p), side (q) and tilted (r) views of the three-dimensional reconstruction model of the TssA dodecamer obtained by electron microscopy (accession number: EMD-3282). The scale bar is 50 Å. Whereas the SAXS model allows to better visualize the arm length compared to the EM reconstruction, its low resolution impairs the visual separation of the dimeric arms.
