FIG. 1.

IcmF and DotU orthologs are found in IAHP gene clusters. The L. pneumophila (L.p.) dotU and icmF genes (shown by red arrows) are located adjacent to a large number of dot/icm genes (shown by blue arrows) and are immediately flanked by genes with no role in type IV secretion (shown by white arrows). The IAHPs from V. cholerae (V.c.), R. leguminosarum (R.l.), and S. enterica (S.e.) all contain orthologs to dotU and icmF (shown by red arrows). The IAHP clusters contain a conserved core set of proteins (shown by solid green arrows) and less well conserved proteins that are found only in a subset of IAHP loci (indicated by stippled or checkered green arrows). Finally, most of these loci also contain a clpB homolog (shown by a black arrow).