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Holmes W and Jogl G  (2006) Crystal structure of inositol phosphate multikinase 2 and implications for substrate specificity. J Biol Chem 281(49):38109-16

Abstract: Inositol polyphosphates perform essential functions as second messengers in eukaryotic cells, and their cellular levels are regulated by inositol phosphate kinases. Most of these enzymes belong to the IPK superfamily, which consists of three subgroups, inositol 3- kinases (IP3Ks), inositol phosphate multikinases (IPMKs) and inositol hexakisphosphate kinases (IP6Ks). IPK family members share several strictly conserved signature motifs and are expected to have the same backbone fold, despite very limited overall amino acid sequence identity. Sequence differences are expected to play important roles in defining the different substrate selectivity of these enzymes. To investigate the structural basis for substrate specificity, we have determined the crystal structure of the yeast IPMK Ipk2 in the apo-form and in a complex with ADP and Mn2+ at up to 2.0 resolution. The overall structure of Ipk2 is related to inositol trisphosphate 3-kinase (an IP3K). The ATP binding site is similar in both enzymes, however, the inositol binding domain is significantly smaller in Ipk2. Replacement of critical side chains in the inositol-binding site suggests how modification of substrate recognition motifs determines enzymatic substrate preference and catalysis.

Status: Published

Type: Journal Article

PubMed ID: 17050532

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