Extended Data Fig. 8: Functional amyloid proteins of Pseudomonas and defense against B. bacteriovorus along with evidence that functional amyloid systems display key characteristics of defense systems.
From: Functional amyloid proteins confer defence against predatory bacteria
(a) Organization of the operon underlying FapC amyloid production along with a graphical representation of how the fibres are formed on the outer membrane97. Briefly, FapBCDEF are secreted via Sec to the periplasmic space. Here FapF forms the secretion apparatus required for FapBCE to cross the outer membrane. Prior to secretion, FapC is proteolytically processed by FapD. FapB is the membrane anchor that seeds FapC oligomerization and fibre formation. FapE serves as the cap of the fibre to stop polymerization. The precise role of FapA is unclear. See Supplementary Table 3 for protein accession numbers. (b) Efficiency of plating, calculated as PFU/mL, of B. bacteriovorus HD100 when infecting the indicated strains of P. aeruginosa. Data are graphed as in Fig. 1b. (c) The length distribution and variance of the indicated families of functional amyloid proteins. For objective comparison, the lengths are normalized by the mean length of the family. The distribution is shown as a box and whisker plot (central measure: median; lower and upper extreme denoted by dashed lines), whereas the variance is shown using the mean (central blue point) with standard deviation bars in blue solid line. (d) The distribution and variance of the measure of exploration of sequence space of selected families of functional amyloid proteins. The exploration of sequence space is measured using two indices, the first of which measures the deviation from the mean amino acid composition and the second of which measures the skew in polarity. The distance from the family centroid in this distribution space is then computed for each sequence. The distribution is shown as a box and whisker plot (central measure: median; lower and upper extreme denoted by dashed lines), whereas the variance is shown using the mean (central point) with standard deviation bars in blue solid line. For (c-d) Grey dots depict outliers; purple numbers are the P-values from a two-sided F-test that compares variances across the two indicated samples. FapE, N = 84; FapC, N = 149; FapB, N = 183; CsgB, N = 305; CsgA, N = 374.
