Figure 5

Identification of highly conserved residues of Nox activator proteins. Abbreviations of species names are shown in Figure 3. (A) Schematic domains structures of p67phox are shown; TPR, the tetratricopeptide repeats; AD, activation domain; ADSIS, AD-SH3 Intervening Sequence; PB1, Phox/Bem 1; OPCA motif, OPR/PC/AID motif. Abbreviations of other domain names are given in Figure 3. Names of orthologs that possess certain domains are shown below the domains. Amino acid residues indicate conserved amino acids in all indicated proteins, and the residue numbers correspond to that of human p67phox.An asterisk indicates that fungal NOXR possess the OPCA motif. Letters in solid boxes indicate residues previously proven by mutational analyses [27] and by X-ray crystallographic structure analysis [28] to be important for binding to Rac (TRP) or p47phox (SH3-B). (B) Molecular taxonomy was built by the length corresponding to the TPR and AD domains. Species names are abbreviated as shown in Figure 3 and as follows: An, A. nidulans; Mg, M. grisea; Fg, F. graminearum. (C-E) Alignments of the AD, ADSIS, and PB1 domains are shown. (C) Letters in a solid box indicate residues that have been proven by mutational analyses to be essential for activation of human Nox2 [30]. Letters in a gray box indicate basic residues that might correlate with a functional PB1 domain. (D) Amino acid residues identical among vertebrate p67phox ortholog sequences are indicated by asterisks. Letters in gray boxes indicate amino acid residues conserved in the putative ADSIS region. (E) Letters in solid boxes indicate the key basic residues required to bind to another PB1 domain, as shown by X-ray crystallographic structural analysis [32]. K355 and K382 indicate lysine residues of the human p67phox. "β1" and "α1" indicate the first β-sheet and the first α-helical structures of PB1 domain [32]. (F) Proposed model for a cooperation of a basic residue of AD (K196 of the human p67phox sequence) with a functional PB1 domain.