The Non-Flagellar Type III Secretion System Evolved from the Bacterial Flagellum and Diversified into Host-Cell Adapted Systems
(A) Representation of the proposed organization of a NF-T3SS system, inspired from the Salmonella system . For consistency with the main text, nomenclature follows that of Yersinia for some genes (see Table S1 for equivalence). Genes in red have homologs in the flagellum (main text, Table S1). “Euka” stands for eukaryotic, “mb” stands for membrane, “IM” for inner membrane, and “OM” for outer membrane. (B) Distribution of the number of different protein profiles of the 9 core genes of NF-T3SS matched per replicon (i-evalue<10−3). Bar colors discriminate between systems in flagella or NF-T3SSs and other systems including only a secretin (SctC) and/or the ATPase (SctN). Numbers of replicons are indicated above the corresponding bars, with the number of uncharacterized cases (“Others”, colored in magenta in bars) in parenthesis if different from the total. “Nb” is an abbreviation for “Number”.