Table 1.
Classification of CSDs based on primary amino acid sequences.
| Enzyme | Organism | Class | Identifier I a | Identifier II b | Identifier III c | |
|---|---|---|---|---|---|---|
| NifS | Azotobacter vinelandii | I | SSGSACTS | Insertion near conserved cysteine | Dimer | |
| IscS | Azotobacter vinelandii | I | SSGSACTS | Insertion near conserved cysteine | ||
| IscS | Helicobacter pylori | I | STGSACAS | Insertion near conserved cysteine | ||
| IscS | Escherichia coli | I | SSGSACTS | Insertion near conserved cysteine | ||
| SufS/CsdB | Escherichia coli | II | RTGHHCA | Insertion near conserved lysine | ||
| CsdA | Escherichia coli | II | RAGQHCA | Insertion near conserved lysine | ||
| SufS | Bacillus subtilis | II | RAGHHCA | Insertion near conserved lysine | ||
| SufS/CSD | Mycobacterium tuberculosis | II | RVGHHCA | Insertion near conserved lysine | ||
| IscS | Mycobacterium tuberculosis | I | STGSACTA | Insertion near conserved cysteine | ||
| CSD | Thermotoga maritima | II | RSGHHCA | Insertion near conserved lysine | ||
| C-DES * | Synechocystis PCC 6714 | Monomer |
a, b, c: CSDs from different organisms can be classified into two main categories based on their sequence identifiers: (I) patch of amino acid sequence neighboring the active site cysteine; (II) presence/absence of amino acid-stretch insertion near the conserved lysine residue coordinating PLP; and (III) 12-amino acid-residue insertion adjacent to the active site cysteine. * C-DES is a novel PLP-dependent L-cyst(e)ine C-S-lyase, which converts cysteine to pyruvate, ammonia, and sulfide.