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. Author manuscript; available in PMC: 2016 Apr 27.
Published in final edited form as: Trends Microbiol. 2000 Aug;8(8):354–360. doi: 10.1016/s0966-842x(00)01792-3

Fig. 1.

Fig. 1

Type IV systems demonstrated or postulated to direct DNA and/or protein translocation. The Agrobacterium tumefaciens T-DNA transfer machine is composed of products of the virB operon and the virD4 gene. Genes encoding VirB and VirD4 homologs are color-coded for the other type IV systems. Dashed lines indicate the genes are physically unlinked. (a) Representative conjugation systems. (b) Transfer systems thought to function as exporters of effector proteins during infection. (c) The Legionella pneumophila Dot/Icm system encodes icmE/dotG and dotB, weak homologs of VirB10 and VirB11, but is clearly ancestrally related to the transfer region of the Shigella flexneri ColIb IncI plasmid. Additional homologies not shown exist between L. pneumophila IcmW, IcmX, IcmV and DotK and the IncI plasmid TraV, TraW, TraX and TraL proteins, respectively. Sources: A. tumefaciens virB (see Ref. 3), pKM101 (Refs 2,47), R388 (Ref. 42), RP4 (Ref. 48), F (Ref. 7), L. pneumophila lvh (Ref. 6), Brucella virB (Ref. 49), Bordetella pertussis ptl (Refs 2,18), Helicobacter pylori cag (Ref. 21), Rickettsia prowazekii (Ref. 50), L. pneumophila dot/icm (Refs 23,24).