Involved in the biosynthesis of the siderophore pyochelin (PubMed:10555976). Adenylates L-cysteine and loads it onto its peptidyl carrier domain via a thioester linkage to the phosphopanthetheine moiety (PubMed:10555976). Then forms a peptide bond between the salicyl-thiazolinyl intermediate bound to the second carrier domain of PchE and the cysteine bound to its own peptidyl carrier domain to form the salicyl-thiazolinyl-cysteinyl-S-PCP2 intermediate. It subsequently cyclizes the C-terminal cysteine to form the second thiazoline heterocycle in the salicyl-thiazolinyl-thiazolinyl-S-PCP2 intermediate (PubMed:10555976). When this intermediate is released by the action of a thioesterase, it produces the tricyclic acid hydroxyphenyl-thiazolyl-thiazolinyl-carboxylic acid (HPTT-COOH), an advanced intermediate containing the aryl-4,2-bis-heterocyclic skeleton of the bithiazoline class of siderophores (PubMed:10555976). ATP + holo-[peptidyl-carrier protein] + L-cysteine = AMP + diphosphate + L-cysteinyl-[peptidyl-carrier protein] kcat is 415 min(-1) with L-cysteine as substrate. Siderophore biosynthesis. Modular protein that contains a condensation/cyclization domain involved in the cyclization of the cysteine, an adenylation domain which activates the cysteine residue into an aminoacyl-AMP ester, a peptidyl carrier protein (PCP2) domain which bears a phosphopantetheinyl arm to attach the activated cysteine and a thioesterase domain (TE) that may release the newly synthesized peptide from the enzyme. Belongs to the NRP synthetase family.