HmuY and GAPDH-Novel Heme Acquisition Strategy in the Oral Microbiome.

The oral cavity of healthy individuals is inhabited by commensals, with species of being the most abundant and prevalent in sites not affected by periodontal diseases. The development of chronic periodontitis is linked with the environmental shift in the oral microbiome, leading to the domination of periodontopathogens. Structure-function studies showed that employs a "moonlighting" protein glyceraldehyde-3-phosphate dehydrogenase (SgGAPDH) to bind heme, thus forming a heme reservoir for exchange with other proteins. Secreted or surface-associated SgGAPDH coordinates Fe(III)heme using His43. Hemophore-like heme-binding proteins of (HmuY), (PinO) and (Tfo) sequester heme complexed to SgGAPDH. Co-culturing of with results in increased gene expression, indicating that HmuY might be required for efficient inter-bacterial interactions. In contrast to the D mutant strain, the wild type strain acquires heme and forms deeper biofilm structures on blood agar plates pre-grown with . Therefore, our novel paradigm of heme acquisition used by appears to extend to co-infections with other oral bacteria and offers a mechanism for the ability of periodontopathogens to obtain sufficient heme in the host environment. Importantly, is advantaged in terms of acquiring heme, which is vital for its growth survival and virulence.