Converts the prephenate produced from the shikimate-chorismate pathway into phenylalanine (PubMed:17726025). Dehydratase that uses arogenate and prephenate as substrates (PubMed:17726025). Utilzes more efficiently arogenate than prephenate (PubMed:17726025). Required for chloroplast division prior to ARC5, but in an ARC3- and ARC6-dependent manner, especially involved in the Z-ring formation (PubMed:30252596). H(+) + L-arogenate = CO2 + H2O + L-phenylalanine H(+) + prephenate = 3-phenylpyruvate + CO2 + H2O Amino-acid biosynthesis; L-phenylalanine biosynthesis; L-phenylalanine from L-arogenate: step 1/1. Amino-acid biosynthesis; L-phenylalanine biosynthesis; phenylpyruvate from prephenate: step 1/1. Observed in chloroplast stromules, and as a ring around the equatorial plane of dividing plastids, thus colocalizing with FtsZ1 and FtsZ2. Expressed in roots, leaves, stems, flowers and siliques. Most abundant in leaves and seeds. Large and misshapen chloroplasts with distorted and irregular outlines.