Characterization of the ABC methionine transporter from Neisseria meningitidis reveals that lipidated MetQ is required for interaction

Abstract

NmMetQ is a substrate-binding protein (SBP) from Neisseria meningitidis that has been identified as a surface-exposed candidate antigen for meningococcal vaccines. However, this location for NmMetQ challenges the prevailing view that SBPs in Gram-negative bacteria are localized to the periplasmic space to promote interaction with their cognate ABC transporter embedded in the bacterial inner membrane. To elucidate the roles of NmMetQ, we characterized NmMetQ with and without its cognate ABC transporter (NmMetNI). Here, we show that NmMetQ is a lipoprotein (lipo-NmMetQ) that binds multiple methionine analogs and stimulates the ATPase activity of NmMetNI. Using single-particle electron cryo-microscopy, we determined the structures of NmMetNI in the presence and absence of lipo-NmMetQ. Based on our data, we propose that NmMetQ tethers to membranes via a lipid anchor and has dual function and localization, playing a role in NmMetNI-mediated transport at the inner membrane and moonlighting on the bacterial surface.

Emerging roles for ABC transporters as virulence factors in uropathogenic Escherichia coli

“…Our work sheds light on the critical role of ABC transporters in UPEC’s survival in the host nutrient niche, host colonization, and subsequent altered phenotypes. Specific transporters from the ABC family have been documented as important in other pathogens as well, including Streptococcus pneumoniae ( 61 ), S. Typhimurium ( 62 ), and Neisseria meningitidis ( 63 ) among others. This study is unique in that we leveraged our transposon mutant library to undertake massive, unbiased screening approaches.…”

Mapping the myristoylome through a complete understanding of protein myristoylation biochemistry

“…A survey of different modified groups has revealed only rare myristoylation (i.e., at R3): 6-10% fatty acylation on proteins and the others saturated or mono-unsaturated C15, C16 (palmitate), C17, and C18 (stearate) acylations [6][7][8]. In Corynebacterium glutamicum, the purified MusE protein harbors only C16 [9], as does Neisseria meningitides MetQ ovexpressed in Escherichia coli [10]. The relative extent of bacterial myristoylation might vary depending on the phylum or the physiological conditions and has been shown to occur in proteins transported to the cytoplasmic membrane by the secretory pathway involving the SecYEG translocon and the twin-arginine transport protein Tat.…”

Molecular basis for substrate transport of Mycobacterium tuberculosis ABC importer DppABCD

“…DppA is predicted to be a lipoprotein and is tethered to the membrane of Mtb with a lipid anchor (25,26). This manner of SBP capture is ubiquitous in Grampositive bacteria and is also found in some Gram-negative bacteria (27,28), preventing SBPs from shuttling freely in the periplasmic space.…”