Figure 6.

Alignment of hydrogenase specific proteases from group 1, 2 and 3d in the phylogenetic tree (Figure 1). Two conserved asparagines (underlined) are believed to be involved in binding to the nickel of the large hydrogenase subunit. Between these asparagines there is a conserved area of unknown function, the so called "HOXBOX". As seen in this figure, although differing among organism, it is in fact conserved within groups of hydrogenase specific proteases i.e. proteases of 3d/HoxW-type. Conserved asparagine (D) containing-regions; light grey, conserved region of unknown function (D(G/C)GT); dark grey and conserved region of unknown function (H(Q/I)L); dark grey, underlined.