Metabolite damage control is a critical but poorly defined aspect of cellular biochemistry, which likely involves many of the so far functionally uncharacterized protein domain (domains of unknown function; DUFs). We have determined the crystal structure of the human DUF89 protein product of the C6ORF211 gene to 1.85 Å. The crystal structure shows that the protein contains a core α-β-α fold with an active site-bound metal ion and α-helical bundle N-terminal cap, which are both conserved features of subfamily III DUF89 domains. The biochemical activities of the human protein are conserved with those of a previously characterized budding yeast homolog, where an in vitro phosphatase activity is supported by divalent cations that include Co²⁺, Ni²⁺, Mn²⁺ or Mg²⁺. Full steady-state kinetics parameters of human DUF89 using a standard PNPP phosphatase assay revealed a six times higher catalytic efficiency in presence of Co²⁺ compared to Mg²⁺. The human enzyme targets a number of phosphate substrates similar to the budding yeast homolog, while it lacks a previously indicated methyltransferase activity. The highest activity on substrate was observed with fructose-1-phosphate, a potent glycating agent, and thus human DUF89 phosphatase activity may also play a role in limiting the buildup of phospho-glycan species and their related damaged metabolites.

• PMID: 32682077
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Journal Article | Research Support, Non-U.S. Gov't | Research Support, U.S. Gov't, Non-P.H.S.

Authors

Dennis TN, Kenjić N, Kang AS, Lowenson JD, Kirkwood JS, Clarke SG, Perry JJP

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