Fig. 1: The stomatin-like protein StlP is important for morphogenesis in S. coelicolor.

A Growth of S. coelicolor M145, its stlP mutant and the complemented strain (∆stlP + pXZ15) measured using a BioLector. Strains were grown in L-phase broth (LPB) medium, and biomass was measured in arbitrary units in triplicates. Error bars represent the standard error of the mean. B Colonies of S. coelicolor M145, the stlP mutant and the complemented strain (∆stlP + pXZ15) after 5 days of growth. C Quantitative measurement of average colony diameters. The number was 17 for the wild-type strain (M145), 58 for the stlP mutant and 56 for the complemented mutant. ***p < 0.001; unpaired two-tailed Student’s t test. D Mycelial morphology of the strains grown on solid L-phase medium agar (LPMA) medium. 16 h-old mycelium was labeled with SYTO-9 (stains nucleic acids; green) and FM5-95 (lipid stain; red). BF brightfield. Cell wall-deficient (CWD) cells are indicated with the white arrowhead. E Stills of Supplementary Movie 1 showing growth of the stlP mutant on LPMA medium. Micrographs were taken every 10 min. F The absence of StlP causes hyperbranching in S. coelicolor. Hyphae were imaged after 16 h of growth on cellophane membranes overlaying LPMA plates. Note that reintroduction of stlP expressed from the constitutive gapAp promoter (pXZ15) restores normal branching in the ∆stlP mutant. G Histograms showing the tip-to-branch distances in hyphae of M145, its stlP mutant and the complemented mutant (∆stlP + pXZ15). Strains were grown for 16 h. The number of tip-to-branch distances was 188 for the wild-type strain (M145), 282 for the stlP mutant and 192 for the complemented mutant. Scale bars represent 5 mm (B), 50 µm (D) and 5 µm (E, F), respectively.