Manganese transport protein C (MntC) (MntC)

Manganese transport protein C (MntC) is a highly conserved, surface-exposed lipoprotein that serves as the substrate-binding component of the MntABC ATP-binding cassette (ABC) transporter system in Staphylococcus aureus and other staphylococcal species [1, 3, 8]. It facilitates the high-affinity acquisition of manganese from the host environment, which is an essential metal ion for bacterial survival and virulence during infection [1, 9]. Manganese acts as a vital cofactor for superoxide dismutase (SOD) enzymes, which protect the pathogen from reactive oxygen species (ROS) produced by host immune cells during the oxidative burst [3, 5, 8]. Beyond nutrient acquisition, MntC has been identified as a contributor to cell adhesion and colonization through its ability to bind host extracellular matrix proteins and plasminogen [6, 10]. Because it is expressed very early during the infectious cycle and is highly conserved across clinical isolates, MntC has been a primary target for the development of anti-staphylococcal vaccines [2, 4]. Therapeutic candidates, such as Pfizer’s four-antigen vaccine SA4Ag (PF-06290510), include recombinant MntC to elicit antibodies that interfere with manganese uptake and promote opsonophagocytic killing by host neutrophils [3, 11]. Despite showing robust protective efficacy in preclinical models, clinical advancement of MntC-targeting vaccines has been difficult. The Phase 2b/3 trial for SA4Ag was discontinued in 2018 due to a lack of efficacy in preventing invasive S. aureus infections in surgical patients, highlighting the complexity of targeting this pathogen [13, 15].

Other names

MntCSitCManganese-binding lipoprotein MntCStaphylococcal manganese transport protein CABC-type manganese transport system substrate-binding proteinABC-type manganese transport system periplasmic componentMtsC

Vaccine antigen targeting bacterial nutrient acquisition and immune evasion; elicits antibodies that inhibit manganese uptake and promote opsonophagocytic killing by neutrophils.