Involved in the biosynthesis of the antibiotic pyoluteorin (PubMed:16162666). Catalyzes the dichlorination of the pyrrole ring of pyrrolyl-S-PltL, generating the 5-chloropyrrolyl-S-PltL intermediate and then the 4,5-dichloropyrrolyl-S-PltL product (PubMed:16162666). (1H-pyrrole-2-carbonyl)-[peptidyl-carrier protein] + 2 chloride + 2 FADH2 + 2 O2 = (4,5-dichloro-1H-pyrrole-2-carbonyl)-[peptidyl-carrier protein] + 2 FAD + 4 H2O (1H-pyrrole-2-carbonyl)-[peptidyl-carrier protein] + chloride + FADH2 + O2 = (5-chloro-1H-pyrrole-2-carbonyl)-[peptidyl-carrier protein] + FAD + 2 H2O (5-chloro-1H-pyrrole-2-carbonyl)-[peptidyl-carrier protein] + chloride + FADH2 + O2 = (4,5-dichloro-1H-pyrrole-2-carbonyl)-[peptidyl-carrier protein] + FAD + 2 H2O Antibiotic biosynthesis. Homodimer. Contains an additional unique helical region at the C-terminus. This C-terminal region blocks a putative substrate-binding cleft, suggesting that a conformational change involving repositioning of this region is necessary to allow binding of the pyrrolyl-S-PltL substrate for its dichlorination by PltA. Belongs to the flavin-dependent halogenase family.