B. Henrissat et al., FUNCTIONAL IMPLICATIONS OF STRUCTURE-BASED SEQUENCE ALIGNMENT OF PROTEINS IN THE EXTRACELLULAR PECTATE LYASE SUPERFAMILY, Plant physiology, 107(3), 1995, pp. 963-976
Pectate lyases are plant Virulence factors that degrade the pectate co
mponent of the plant cell wall. The enzymes share considerable sequenc
e homology with plant pollen and style proteins, suggesting a shared s
tructural topology and possibly functional relationships as well. The
three-dimensional structures of two Erwinia chrysanthemi pectate lyase
s, C and E, have been superimposed and the structurally conserved amin
o acids have been identified. There are 232 amino acids that superimpo
se with a root-mean-square deviation of 3 Angstrom or less. These amin
o acids have been used to correct the primary sequence alignment deriv
ed from evolution-based techniques. Subsequently, multiple alignment t
echniques have allowed the realignment of other extracellular pectate
lyases as well as all sequence homologs, including pectin lyases and t
he plant pollen and style proteins. The new multiple sequence alignmen
t reveals amino acids likely to participate in the parallel beta helix
motif, those involved in binding Ca2+, and those invariant amino acid
s with potential catalytic properties. The latter amino acids cluster
in two well-separated regions on the pectate lyase structures, suggest
ing two distinct enzymatic functions for extracellular pectate lyases
and their sequence homologs.