ATP-dependent unfoldase that stimulates the incorporation of the pyridoxal phosphate cofactor into 5-aminolevulinate synthase (HEM1), thereby activating 5-aminolevulinate (ALA) synthesis, the first step in heme biosynthesis. Up-regulates heme biosynthesis. Homohexamer that forms a ring structure; this hexamerization requires ATP binding (By similarity). Interacts with HEM1 (PubMed:25957689). 5-fold reduced production of the first heme precursor 5-aminolevulinic acid (ALA) and 2-fold reduction in total heme. In combination with a disruption of HEM25 or an inactivated HEM1, abrogates mitochondrial respiration. Present with 10900 molecules/cell in log phase SD medium. Belongs to the ClpX chaperone family.