Fig 9.

Intriguing gene cluster arrangements that have functional implications. The top panel illustrates the linkage of glmM and glmS, the first two genes of the lipid II pathway from fructose-6-P (see Fig. 7), with tyrP in species of Chlamydiaceae and “Ca. Protochlamydia amoebophila.” The TyrP gene product is a Trp transporter. In the top grouping, two species of Chlamydia and two strains of Chlamydophila pneumoniae have tandem gene duplicates of tyrP, designated tyrP-1 and tyrP-2. In addition, the Chlamydiaceae organisms possess two linked genes that function in cell division; these genes are not linked to glmM and glmS in “Ca. Protochlamydia amoebophila.” Genes that are depicted as yellow arrows encode enzymes whose functional roles are illustrated in Fig. 7. In the bottom panel, two linkage regions (separated by a dashed line) are shown which have become separated from the extensive putative ancestral sequence of 16 genes given in blue at the top of the panel. Hypo, hypothetical protein gene.