Determining proteins that specifically bind to polyphosphate in osteoblasts

Abstract

Inorganic polyphosphate (polyP) was once obscure and disregarded as a ‘molecular fossil’ but is now clearly emerging as a fundamental molecule of interest. Our current motivation is to elucidate the mechanisms of polyP as a pivotal molecule in osteoblasts, from synthesis to function. Preliminary data from gel electrophoresis showed that polyP binds specifically to various proteins in osteoblasts. By chemically cross-linking the terminal phosphate of polyP with biotin via a phosphoramidate linkage for attachment to streptavidin-coated magnetic beads, an affinity chromatography approach could be taken to identify candidate proteins that interact functionally with polyP. Several proteins identified via mass spectrometry showed good prospects for further investigating polyP’s chaperoning ability and involvement in gene transcription. Coupled with the development of fluorophore- and Nanogold-conjugated polyphosphate binding domain as highly-specific probes for polyP localisation studies, emerging evidence will transform existing views of the implications of polyP-protein binding to a vibrant field of inquiry.