title: The Mycobacterium tuberculosis secreted protein Rv0203 transfers heme to membrane proteins MmpL3 and MmpL11.
abstract: Mycobacterium tuberculosis is the causative agent of tuberculosis, which is becoming an increasingly global public health problem due to the rise of drug-resistant strains. While residing in the human host, M. tuberculosis needs to acquire iron for its survival. M. tuberculosis has two iron uptake mechanisms, one that utilizes non-heme iron and another that taps into the vast host heme-iron pool. To date, proteins known to be involved in mycobacterial heme uptake are Rv0203, MmpL3, and MmpL11. Whereas Rv0203 transports heme across the bacterial periplasm or scavenges heme from host heme proteins, MmpL3 and MmpL11 are thought to transport heme across the membrane. In this work, we characterize the heme-binding properties of the predicted extracellular soluble E1 domains of both MmpL3 and MmpL11 utilizing absorption, electron paramagnetic resonance, and magnetic circular dichroism spectroscopic methods. Furthermore, we demonstrate that Rv0203 transfers heme to both MmpL3-E1 and MmpL11-E1 domains at a rate faster than passive heme dissociation from Rv0203. This work elucidates a key step in the mycobacterial uptake of heme, and it may be useful in the development of anti-tuberculosis drugs targeting this pathway.
authors.affiliation: Department of Molecular Biology and Biochemistry, University of California at Irvine, Irvine, California 92697, USA.
authors.forename: Cedric P
authors.initials: CP
authors.lastname: Owens
authors.forename: Nicholas
authors.initials: N
authors.lastname: Chim
authors.forename: Amanda B
authors.initials: AB
authors.lastname: Graves
authors.forename: Christine A
authors.initials: CA
authors.lastname: Harmston
authors.forename: Angelina
authors.initials: A
authors.lastname: Iniguez
authors.forename: Heidi
authors.initials: H
authors.lastname: Contreras
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Liptak
authors.forename: Celia W
authors.initials: CW
authors.lastname: Goulding
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites / Q000235:genetics; D001692:Biological Transport; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002942:Circular Dichroism; D004578:Electron Spin Resonance Spectroscopy; D004591:Electrophoresis, Polyacrylamide Gel; D006418:Heme / Q000378:metabolism*; D006420:Hemeproteins / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D008665:Metalloporphyrins / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011994:Recombinant Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014376:Tuberculosis / Q000382:microbiology
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D006420:Hemeproteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D008665:Metalloporphyrins; D011994:Recombinant Proteins; D006418:Heme; C058069:zinc mesoporphyrin
keywords: Heme; Heme Uptake Pathway; Iron; Iron Acquisition; Kinetics; Mycobacterium tuberculosis; Protein Domains; Transport