Fig. 4: PilA, minor pilins, and PilY1 make up the short stem and plug.
From: PilY1 and minor pilins form a complex priming the type IVa pilus in Myxococcus xanthus
a Structures (subtomogram averages) of T4aPM in strains of the indicated genotypes. Top row, central slices through subtomogram averages of empty T4aPM. Lower row, first panel describes densities observed in subtomogram average of empty WT T4aPM (see also Fig. 1a) as described in ref. 3, panels 2–5 show differences between T4aPM in mutants versus the WT (lacking densities, yellow), and panels 6 and 7 the difference between T4aPM in SA7791 (∆1∆2cluster ∆pilY1.3 + PilY1.3-sfGFP) and SA8764 (∆1∆2cluster ∆pilY1.3 + PilY1.3∆vWFA-FLAG) versus T4aPM in ∆1∆2cluster structure (lacking densities, yellow; extra density, red). Panels 1, 3, and 4 in both rows are from ref. 3 (reprinted with permission from AAAS). Scale bar, 10 nm. b Model of T4aPM priming complex. Panel 1, component map of non-piliated T4aPM with priming complex and proteins assigned to the densities in the subtomogram average of the non-piliated WT T4aPM; for simplicity, PilB and PilT are not shown separately. Panel 2, hypothetical structural model of priming complex after low-pass filtering to 3-nm resolution and placed into the subtomogram average of non-piliated WT T4aPM.
