Figure 4.

Hfx. volcanii AglD Asp201 is apparently the catalytic base of the enzyme. Site-directed mutagenesis was performed to generate CBD-AglD containing mutations of Asp173 (upper left column), Asp195 (lower left column), and Asp201 (right column), as listed on the left of each panel. For each mutant, the upper and lower panels, respectively, show the Coomassie- and PAS-stained S-layer glycoprotein from the background strain (lanes 1 and 5), from the aglD deletion strain (lane 2), from the aglD deletion strain complemented with a plasmid encoding CBD-AglD (lane 3), or from the aglD deletion strain complemented with a plasmid encoding CBD fused to mutated AglD (lane 4).