A single amino acid change converts Aurora-A into Aurora-B-like kinase in terms of partner specificity and cellular function

Aurora kinase-A and -B are key regulators of the cell cycle and tumorigenesis. It has remained a mystery why these 2 Aurora kinases, although highly similar in protein sequence and structure, are distinct in subcellular localization and function. Here, we report the striking finding that a single amino acid residue is responsible for these differences. We replaced the Gly-198 of Aurora-A with the equivalent residue Asn-142 of Aurora-B and found that in HeLa cells, Aurora-A G198N was recruited to the inner centromere in metaphase and the midzone in anaphase, reminiscent of the Aurora-B localization. Moreover, Aurora-A G198N compensated for the loss of Aurora-B in chromosome misalignment and cell premature exit from mitosis. Furthermore, Aurora-A G198N formed a complex with the Aurora-B partners, INCENP and Survivin, and its localization depended on this interaction. Aurora-A G198N phosphorylated the Aurora-B substrates INCENP and Survivin in vitro. Therefore, we propose that the presence of Gly or Asn at a single site assigns Aurora-A and -B to their respective partners and thus to their distinctive subcellular localizations and functions.