6MT2
Crystal structure of Inorganic Pyrophosphatase from Medicago truncatula (I23 crystal form)
Summary for 6MT2
| Entry DOI | 10.2210/pdb6mt2/pdb |
| Related | 4lug 5ls0 |
| Descriptor | Soluble inorganic pyrophosphatase (2 entities in total) |
| Functional Keywords | pyrophosphate, ppa, autoproteolysis, hydrolase |
| Biological source | Medicago truncatula (Barrel medic) |
| Total number of polymer chains | 4 |
| Total formula weight | 98624.89 |
| Authors | Ruszkowski, M.,Grzechowiak, M.,Dauter, Z. (deposition date: 2018-10-18, release date: 2019-08-14, Last modification date: 2023-10-11) |
| Primary citation | Grzechowiak, M.,Ruszkowski, M.,Sliwiak, J.,Szpotkowski, K.,Sikorski, M.,Jaskolski, M. Crystal structures of plant inorganic pyrophosphatase, an enzyme with a moonlighting autoproteolytic activity. Biochem.J., 476:2297-2319, 2019 Cited by PubMed Abstract: Inorganic pyrophosphatases (PPases, EC 3.6.1.1), which hydrolyze inorganic pyrophosphate to phosphate in the presence of divalent metal cations, play a key role in maintaining phosphorus homeostasis in cells. DNA coding inorganic pyrophosphatases from (PPA1) and (PPA1) were cloned into a bacterial expression vector and the proteins were produced in cells and crystallized. In terms of their subunit fold, PPA1 and PPA1 are reminiscent of other members of Family I soluble pyrophosphatases from bacteria and yeast. Like their bacterial orthologs, both plant PPases form hexamers, as confirmed in solution by multi-angle light scattering and size-exclusion chromatography. This is in contrast with the fungal counterparts, which are dimeric. Unexpectedly, the crystallized PPA1 and PPA1 proteins lack ∼30 amino acid residues at their N-termini, as independently confirmed by chemical sequencing. , self-cleavage of the recombinant proteins is observed after prolonged storage or during crystallization. The cleaved fragment corresponds to a putative signal peptide of mitochondrial targeting, with a predicted cleavage site at Val31-Ala32. Site-directed mutagenesis shows that mutations of the key active site Asp residues dramatically reduce the cleavage rate, which suggests a moonlighting proteolytic activity. Moreover, the discovery of autoproteolytic cleavage of a mitochondrial targeting peptide would change our perception of this signaling process. PubMed: 31371393DOI: 10.1042/BCJ20190427 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (2.89 Å) |
Structure validation
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