Figure 6.

(A) Alignment of the C-terminal portion of the novel PsuX protein sequence family (the full-length alignment is available upon request). The overlining denotes a highly conserved stretch of the PsuX alignment that contains two Asp residues and is reminiscent of a Ψ synthase motif (B). GenBank accession numbers for the PsuX sequences are: P.horikoshii, BAA30059; P.abyssi, CAB49759; M.jannaschii, Q60346; M.thermoautotrophicum, AAB85800; A.fulgidus, AAB90092; A.pernix, BAA79514; C.elegans, CAB60423; D.melanogaster (translation of open reading frame in GenBank accession number AC005334). The portions of the A.pernix and E.gracilis Cbf5p sequences that display similarity to the PsuX sequences are shown at the bottom of the alignment; these Cbf5p sequences correspond to K57 to L132 of accession number BAA79974 (A.pernix) and K127 to L205 (E.gracilis; see Fig. 2). Shading of residues is as described in Figure 5. (B) Alignment of different classes of Ψ synthase motifs (77) plus the overlined PsuX stretch shown in (A). Highly conserved positions are shown, with non-conserved positions indicated by ‘x’. Because the putative PsuX motif contains two Asp residues that might correspond to the catalytic Asp (indicated by the asterisk) in known Ψ synthases, two slightly different alignments are shown.