The cytosolic HinT protein of Mycoplasma hominis interacts with two membrane proteins.

Histidine triad nucleotide-binding (HinT) proteins are dimeric proteins that bind to purines and are found in all three kingdoms: the eukarya, bacteria and archaea. In eukaryotes, HinT proteins have been detected intracellularly, but their function is unknown. Until now, knowledge about HinT proteins in prokaryotes was restricted to sequence similarities and nucleotide-binding studies. In this study, we provide evidence that, in the cell wall-less prokaryote, Mycoplasma hominis, the gene encoding the HinT protein forms an operon with two other genes. These genes encode the species-specific membrane proteins, P60 and P80, which are associated within the mycoplasma membrane. The finding that HinT interacts with this complex by binding to P80 provides novel insight into the organization of bacterial HinT proteins.