Figure 4: Proposed mechanism for evolution of Zn-GlxI.

The arrows represent point of acquisition of Zn-GlxI from Candidatus pelagibacter (Cp) [black] and Sphingomonas (Sp) [green] in ancestors of eukaryotes and plants respectively. Loss of single domain Zn-GlxI has been marked as red asterisks whereas loss of two-domain Zn-GlxI has been shown by yellow astericks. The box depicts the scheme of evolution of single and two-domain Zn-GlxI in the ancestor of Brown algae and Diatoms (in blue color). Broken arrow represents absence of GlxI in the corresponding sub-division. Modified from Ref. 50. Reprinted with permission from AAAS.