Aconitase X (AcnX) is a subfamily of Acn superfamily. It is encoded in the genomes of many archaea, proteobacteria and fungi. Among archaea, the pattern of aconitase X occurrence complements that of aconitase A such that together the two enzymes account for aconitase activity in all archaea [1]. This protein catalyzes the dehydration of cis-3-hydroxy-L-proline to delta1-pyrroline-2-carboxylate [2].

1: Filling a gap in the central metabolism of archaea: prediction of a novel aconitase by comparative-genomic analysis. Makarova KS, Koonin EV; FEMS Microbiol Lett. 2003;227:17-23. PMID:14568143

2: Functional characterization of aconitase X as a cis-3-hydroxy-L-proline dehydratase. Watanabe S, Tajima K, Fujii S, Fukumori F, Hara R, Fukuda R, Miyazaki M, Kino K, Watanabe Y; Sci Rep. 2016;6:38720. PMID:27929065