Sulfatases catalyze the hydrolysis of
sulfate ester bonds from a wide variety of substrates. Several human inherited diseases are caused by the deficiency of individual
sulfatases, while in patients with
multiple sulfatase deficiency mutations in the
Sulfatase Modifying Factor 1 (SUMF1) gene cause a defect in the post-translational modification of a
cysteine residue into
C(alpha)-formylglycine (FGly) at the active site of all
sulfatases. This unique modification mechanism, which is required for catalytic activity, has been highly conserved during evolution. Here, we used a genomic approach to investigate the relationship between
sulfatases and their modifying factors in humans and several model systems. First, we determined the complete catalog of human
sulfatases, which comprises 17 members (versus 14 in rodents) including four novel ones (ARSH, ARSI, ARSJ and ARSK). Secondly, we showed that the active site, which is the target of the post-translational modification, is the most evolutionarily constrained region of
sulfatases and shows intraspecies sequence convergence. Exhaustive sequence analyses of available
proteomes indicate that
sulfatases are the only likely targets of their modifying factors. Thirdly, we showed that
sulfatases and ectonucleotide
pyrophosphatases share significant homology at their active sites, suggesting a common evolutionary origin as well as similar catalytic mechanisms. Most importantly, gene association studies performed on prokaryotes suggested the presence of at least two additional mechanisms of
cysteine-to-FGly conversion, which do not require SUMF1. These results may have important implications in the study of diseases caused by
sulfatase deficiencies and in the development of therapeutic strategies.