1U32

Crystal structure of a Protein Phosphatase-1: Calcineurin Hybrid Bound to Okadaic Acid

Summary for 1U32

• Entry DOI: 10.2210/pdb1u32/pdb
• Descriptor: Serine/threonine protein phosphatase PP1-gamma catalytic subunit, MANGANESE (II) ION, OKADAIC ACID, ... (5 entities in total)
• Functional Keywords: hydrolase
• Biological source: Homo sapiens (human)
• Cellular location: Cytoplasm: P36873
• Total number of polymer chains: 1
• Total formula weight: 34921.19

Authors

Maynes, J.T.,Perreault, K.R.,Cherney, M.M.,Luu, H.A.,James, M.N.G.,Holmes, C.F.B. (deposition date: 2004-07-20, release date: 2004-08-17, Last modification date: 2023-10-25)

Primary citation

Maynes, J.T.,Perreault, K.R.,Cherney, M.M.,Luu, H.A.,James, M.N.G.,Holmes, C.F.B.
Crystal Structure and Mutagenesis of a Protein Phosphatase-1:Calcineurin Hybrid Elucidate the Role of the {beta}12-{beta}13 Loop in Inhibitor Binding
J.Biol.Chem., 279:43198-43206, 2004

PubMed Abstract: Protein phosphatase-1 and protein phosphatase-2B (calcineurin) are eukaryotic serine/threonine phosphatases that share 40% sequence identity in their catalytic subunits. Despite the similarities in sequence, these phosphatases are widely divergent when it comes to inhibition by natural product toxins, such as microcystin-LR and okadaic acid. The most prominent region of non-conserved sequence between these phosphatases corresponds to the beta12-beta13 loop of protein phosphatase-1, and the L7 loop of toxin-resistant calcineurin. In the present study, mutagenesis of residues 273-277 of the beta12-beta13 loop of the protein phosphatase-1 catalytic subunit (PP-1c) to the corresponding residues in calcineurin (312-316), resulted in a chimeric mutant that showed a decrease in sensitivity to microcystin-LR, okadaic acid, and the endogenous PP-1c inhibitor protein inhibitor-2. A crystal structure of the chimeric mutant in complex with okadaic acid was determined to 2.0-A resolution. The beta12-beta13 loop region of the mutant superimposes closely with that of wild-type PP-1c bound to okadaic acid. Systematic mutation of each residue in the beta12-beta13 loop of PP-1c showed that a single amino acid change (C273L) was the most influential in mediating sensitivity of PP-1c to toxins. Taken together, these data indicate that it is an individual amino acid residue substitution and not a change in the overall beta12-beta13 loop conformation of protein phosphatase-1 that contributes to disrupting important interactions with inhibitors such as microcystin-LR and okadaic acid.

PubMed: 15280359
DOI: 10.1074/jbc.M407184200

Experimental method

X-RAY DIFFRACTION (2 Å)