FIGURE 3.

Structural and enzymatic characteristics of ADHE. A, the C. reinhardtii enzyme consists of an N-terminal ALDH domain (cd07077) followed by a C-terminal ADH domain (cd08178). The catalytic Cys residue in the ALDH domain (Cys³²³) is indicated. Two signatures for iron-binding were identified in the ADH domain: ADH_iron_1 (residues 706–734) (Prosite PS00913) and ADH_iron_2 (residues 794–814) (Prosite PS00060). The position of the residues potentially involved in iron coordination (Asp⁷²⁷, His⁷³¹, His⁷⁹⁷, and His⁸¹¹) was inferred from the structure of the E. coli iron-dependent alcohol dehydrogenase FucO (69). Black boxes indicate NADH binding sites (Gly²⁷⁰–Gly²⁹¹ and Glu⁵⁹⁹–Met⁶²²) based on (70). Compared with bacterial enzymes, the algal ADHE exhibits at its N terminus an extension (gray box), which likely serves for intracellular targeting. B, enzymatic activities catalyzed by ADHE.