Involved in the biosynthesis of petrobactin, a catecholate siderophore that functions in both iron acquisition and virulence (PubMed:17189355, PubMed:18955706). Catalyzes the conversion of 3-dehydroshikimate to 3,4-dihydroxybenzoate (3,4-DHBA) (PubMed:18955706). 3-dehydroshikimate = 3,4-dihydroxybenzoate + H2O Binds 1 Mn(2+) ion per subunit. Optimum pH is >9.5. Aromatic compound metabolism; 3,4-dihydroxybenzoate biosynthesis; 3,4-dihydroxybenzoate from 3-dehydroquinate: step 2/2. Siderophore biosynthesis; petrobactin biosynthesis. Homodimer. The deletion mutant cannot produce petrobactin on iron-depleted medium. In vitro analysis show that mutants grow to a very limited extent as vegetative cells in iron-depleted medium but are not able to outgrow from spores under the same culture conditions.