Figure 6. Alignment of YZGD with other members of the nitrophenyl phosphatase family.

The amino acid sequences of YZGD, NAGD from E. coli, the p-nitrophenyl phosphatases (pNppase) from S. pombe and S. cerevisiae and the human PLPase were aligned using CLUSTAL X [26]. Similar and identical amino acids are in boldface. Gaps in the amino acid sequences inserted to optimize alignment are indicated by a ‘-’. Motifs I, II and III of the HAD superfamily are underlined and labelled. The 23 amino acid Nudix signature sequence in YZGD is in boldface. The amino acids Asp¹² (within the HAD domain of YZGD) and Glu³²⁴ (within the Nudix signature sequence of YZGD), which were modified by site-directed mutagenesis, are highlighted in grey. The [S/T]NN and [F/W/Y][I/L/V] motifs, which appear to be predictive markers for the nitrophenyl phosphatase family are denoted by a ‘*’, as are the conserved serine between motifs I and II and the conserved GKP sequence of motif III.