Is the bacteriophage lambda lysozyme an evolutionary link or a hybrid between the C and V-type lysozymes? Homology analysis and detection of the catalytic amino acid residues.
The relationship between the bacteriophage lambda lysozyme (lambda L) and the C and V-type lysozymes has been investigated by sequence alignment, secondary structure prediction and pattern recognition methods. The alignment of the amino terminal part of lambda L with that of V-type lysozymes suggests that Glu19 is a residue essential for catalysis. Its mutation to Gln leads to a completely inactive enzyme. In the alignment of the sequence of lambda L with those of the C-type lysozymes a strongly homologous fragment of about 30 amino acid residues is detected. Taking into consideration this observation and the published structural alignments between C and V-type lysozymes, a repetition of the beta-sheet motif in lambda L is proposed. The multiple alignment draws the attention to a possible catalytic role for Asp34 that would be positioned in the middle of the second strand of the beta-sheet as in the C-type lysozymes. This role is confirmed by mutagenesis. The implications of these observations in terms of the evolutionary relationship between lambda L and the other lysozymes is discussed.
Jespers
L
L
Laboratoire de Biochimie Physique et des Biopolymères, Université Catholique de Louvain, Belgium.
Sonveaux
E
E
Fastrez
J
J
D000595:Amino Acid Sequence; D010582:Bacteriophage lambda / Q000201:enzymology* / Q000235:genetics; D001483:Base Sequence; D001665:Binding Sites; D005075:Biological Evolution; D004277:DNA, Single-Stranded; D008969:Molecular Sequence Data; D009113:Muramidase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D017386:Sequence Homology, Amino Acid
D004277:DNA, Single-Stranded; D009113:Muramidase