title: Partial complementation of Sinorhizobium meliloti bacA mutant phenotypes by the Mycobacterium tuberculosis BacA protein.
abstract: The Sinorhizobium meliloti BacA ABC transporter protein plays an important role in its nodulating symbiosis with the legume alfalfa (Medicago sativa). The Mycobacterium tuberculosis BacA homolog was found to be important for the maintenance of chronic murine infections, yet its in vivo function is unknown. In the legume plant as well as in the mammalian host, bacteria encounter host antimicrobial peptides (AMPs). We found that the M. tuberculosis BacA protein was able to partially complement the symbiotic defect of an S. meliloti BacA-deficient mutant on alfalfa plants and to protect this mutant in vitro from the antimicrobial activity of a synthetic legume peptide, NCR247, and a recombinant human β-defensin 2 (HBD2). This finding was also confirmed using an M. tuberculosis insertion mutant. Furthermore, M. tuberculosis BacA-mediated protection of the legume symbiont S. meliloti against legume defensins as well as HBD2 is dependent on its attached ATPase domain. In addition, we show that M. tuberculosis BacA mediates peptide uptake of the truncated bovine AMP, Bac7(1-16). This process required a functional ATPase domain. We therefore suggest that M. tuberculosis BacA is important for the transport of peptides across the cytoplasmic membrane and is part of a complete ABC transporter. Hence, BacA-mediated protection against host AMPs might be important for the maintenance of latent infections.
authors.affiliation: School of Medicine & Dentistry, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, United Kingdom.
authors.forename: M F F
authors.initials: MF
authors.lastname: Arnold
authors.forename: A F
authors.initials: AF
authors.lastname: Haag
authors.forename: S
authors.initials: S
authors.lastname: Capewell
authors.forename: H I
authors.initials: HI
authors.lastname: Boshoff
authors.forename: E K
authors.initials: EK
authors.lastname: James
authors.forename: R
authors.initials: R
authors.lastname: McDonald
authors.forename: I
authors.initials: I
authors.lastname: Mair
authors.forename: A M
authors.initials: AM
authors.lastname: Mitchell
authors.forename: B
authors.initials: B
authors.lastname: Kerscher
authors.forename: T J
authors.initials: TJ
authors.lastname: Mitchell
authors.forename: P
authors.initials: P
authors.lastname: Mergaert
authors.forename: C E
authors.initials: CE
authors.lastname: Barry
authors.forename: M
authors.initials: M
authors.lastname: Scocchi
authors.forename: M
authors.initials: M
authors.lastname: Zanda
authors.forename: D J
authors.initials: DJ
authors.lastname: Campopiano
authors.forename: G P
authors.initials: GP
authors.lastname: Ferguson
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D005816:Genetic Complementation Test; D000455:Medicago sativa / Q000382:microbiology / Q000502:physiology; D026901:Membrane Transport Proteins / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism*; D009169:Mycobacterium tuberculosis / Q000235:genetics*; D016962:Sinorhizobium meliloti / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D013559:Symbiosis; D023083:beta-Defensins / Q000494:pharmacology
chemical_list: D000890:Anti-Infective Agents; D001426:Bacterial Proteins; C106641:DEFB4A protein, human; D026901:Membrane Transport Proteins; C082397:bacA protein, Rhizobium meliloti; D023083:beta-Defensins