Shr of group A streptococcus is a new type of composite NEAT protein involved in sequestering haem from methaemoglobin

摘要: A growing body of evidence suggests that surface or secreted proteins with NEAr Transporter (NEAT) domains play a central role in haem acquisition and trafficking across the cell envelope Gram-positive bacteria. Group streptococcus (GAS), β-haemolytic human pathogen, expresses NEAT protein, Shr, which binds several haemoproteins extracellular matrix (ECM) components. Shr is complex, membrane-anchored unique N-terminal domain (NTD) two separated by leucine-rich repeat region. In this study we have carried out an analysis functional Shr. We show obtains solution furthermore reduces iron; first report reduction protein. More specifically, demonstrate both constituent are responsible for binding haem, although they missing critical tyrosine residue found ligand-binding pocket other haem-binding domains. Further investigations previously undescribed region within NTD interacts methaemoglobin. domains, however, do not contribute significantly to methaemoglobin but mediate ECM components fibronectin laminin. protein fragment containing plus was be sufficient sequester directly from Correlating these vitro findings vivo biological function, mutants establishes GAS growth as sole source iron, indicates at least one necessary utilization suggest prototype new group composite involved uptake pyogenic streptococci Clostridium novyi.