A manganese transporter, BB0219 (BmtA), is required for virulence by the Lyme disease spirochete, Borrelia burgdorferi

Abstract

Borrelia burgdorferi (Bb), the causative agent of Lyme disease, is transmitted to mammalian hosts through an arthropod (tick) vector. To establish infection, Bb must acquire essential nutrients, including transition metals, from its mammalian and tick hosts. Thus far, no metal transporter has been identified in Bb. Here, we report the identification of the first metal transporter, BmtA (BB0219), in Bb. BmtA-deficient mutants of virulent Bb were readily generated, and the mutants grew slightly slower than wild-type Bb in vitro. However, BmtA mutants were sensitive to the chelating actions of EDTA, suggesting a role for BmtA in metal utilization. Intracellular accumulation of manganese (Mn) was substantially diminished in the bmtA mutant, indicating that BmtA was operative in Mn uptake. Given that BmtA lacks homology to any known Mn transporter, we postulate that BmtA is part of a novel mechanism for Mn acquisition by a bacterial pathogen. BmtA also was essential to the infectious life cycle of Bb in ticks and mammals, thereby qualifying BmtA as a new borrelial virulence factor. In addition, the bmtA mutant was sensitive to treatment with t-butyl hydroperoxide, implying that BmtA, and thus Mn, is important to Bb for detoxifying reactive oxygen species, including those potentially liberated by immune effector cells during the innate immune response. Our discovery of the first molecule involved in metal transport in Bb provides a foundation for further elucidating metal homeostasis in this important human pathogen, which may lead to new strategies for thwarting Lyme disease. metal transport ͉ pathogenesis

Overexpression of CsrA (BB0184) Alters the Morphology and Antigen Profiles ofBorrelia burgdorferi

“…In addition, the location of csrA Bb was adjacent to the ORFs that were previously characterized as being part of the flgK (bb0180 to bb0183) motility operon (34). By employing an RT-PCR-based method (34,62), we were able to show that bb0184 or csrA Bb is cotranscribed with its upstream neighbors bb0182 and bb0183. Based on these observations, it can be stated that csrA Bb is the terminal ORF of the flgK motility operon.…”

“…. In order to determine if csrA Bb is indeed a part of the flgK operon, we performed RT-PCR using primers specific to csrA Bb and to regions up-and downstream of csrA Bb similar to procedures described previously (34,62). As shown in Fig.…”

CsrA (BB0184) Is Not Involved in Activation of the RpoN-RpoS Regulatory Pathway in Borrelia burgdorferi

“…RNA isolation was performed as previously described (21,22,63). Briefly, total RNA was isolated using the TRIzol reagent according to the manufacturer's instructions.…”

“…Plasmid pALH384 or pOY236 was then electroporated into B. burgdorferi 297 or B31, respectively, to create the csrA mutants. Transformation of B. burgdorferi was performed as previously described (33,63,64).…”

Structural and Functional Characterization of an Orphan ATP-Binding Cassette ATPase Involved in Manganese Utilization and Tolerance in Leptospira spp

“…Among divalent cations, manganese has recently received attention. Indeed, mutation of the Mn 2ϩ uptake system was shown to impair the virulence of several bacterial species, including Salmonella enterica serovar Typhimurium (10), Yersinia pestis (11), Bacillus anthracis (12), Streptococcus pneumoniae (13), Staphylococcus aureus (14), and Borrelia burgdorferi (15). Moreover, exporting excess Mn 2ϩ has also proven necessary for infection by S. pneumoniae (16), Xanthomonas oryzae (17), and Neisseria meningitidis (18).…”