J. Biol. Chem., Vol. 260, Issue 5, 2794-2797, 03, 1985
Pyruvoyl-dependent histidine decarboxylases. Comparative sequences of cysteinyl peptides of the enzymes from Lactobacillus 30a, Lactobacillus buchneri, and Clostridium perfringens
QK Huynh and EE Snell
The two cysteinyl residues present in histidine decarboxylase from
Lactobacillus 30a differ greatly in reactivity. One (class 1) reacts
readily in the native state with dithiobis-(2-nitrobenzoate) with complete
loss of enzyme activity; the other (class 2) reacts only after denaturation
of the enzyme (Lane, R. S., and Snell, E. E. (1976) Biochemistry 15,
4175-4179). These differences in reactivity permitted use of covalent
(disulfide) chromatography to isolate separate peptides that contain these
two residues. Sequence analysis showed that the class 1 cysteinyl residue
is at position 147 in a hydrophilic portion of the alpha chain (Huynh, Q.
K., Recsei, P. A., Vaaler, G. L., and Snell, E. E. (1984) J. Biol. Chem.
259, 2833-2839), while the class 2 cysteinyl residue is present at position
71, adjacent to a hydrophobic portion of the same chain. Cysteinyl peptides
identical with or homologous to the class 2 cysteinyl peptide of the
Lactobacillus 30a enzyme were isolated from the alpha subunits of histidine
decarboxylases from Lactobacillus buchneri and Clostridium perfringens,
respectively. The L. buchneri enzyme also contained a peptide homologous to
the class 1 cysteinyl peptide from Lactobacillus 30a. However, no
corresponding peptide was present in the enzyme from C. perfringens, in
which the second cysteinyl residue of the alpha chain occupies position 3,
very near the essential pyruvoyl residue. This enzyme, unlike those from
Lactobacillus 30a or L. buchneri, also contains one cysteinyl residue in
its beta chain. Although Cys 147 is an active site residue in histidine
decarboxylase from Lactobacillus 30a, the absence of a corresponding
residue in the C. perfringens enzyme confirms previous indications (Recsei,
P. A., and Snell, E. E. (1982) J. Biol. Chem. 257, 7196-7202) that this SH
group is not essential for decarboxylase action.