Fig. 4.

Role of EssC in EsxA and EsxB secretion. (A) Predicted topology of EssC with insertion sites of bursa aurealis in each strain (filled triangles). EssC contains two FstK/SpoIIIE-like domains (FSD). (B) Immunoblotting of total cellular protein (T) or culture medium (MD) with α-EsxA and α-EsxB antibodies. Insertional mutations at codon 264 (mutant 1) and codon 618 (mutant 2) prevented production/secretion of EsxA and EsxB. Mutants 1–4 are strains ΦNΞ 04464 (insertion at codon 264), ΦNΞ 02191 (insertion at codon 618), ΦNΞ 02832 (insertion at codon 721), and ΦNΞ 13038 (insertion at codon 1279), respectively. α-SrtA was used as a control for the total protein loaded.