title: Interaction of the sensor module of Mycobacterium tuberculosis H37Rv KdpD with members of the Lpr family.
abstract: The genetic and biochemical mechanisms by which Mycobacterium tuberculosis senses and responds to the complex environment that it encounters during infection and persistence within the host remain unknown. In a number of bacterial species, the Kdp signal transduction pathway appears to be the primary response to environmental osmotic stress, which is primarily mediated by K+ concentration in bacteria. We show that kdp encodes for components of a mycobacterial signalling pathway by demonstrating the K+ dependence of kdpFABC expression in both M. tuberculosis H37Rv and Mycobacterium smegmatis. To identify proteins of M. tuberculosis that participate in this signalling pathway, we used the N-terminal sensing module of the histidine kinase KdpD as bait in a yeast two-hybrid screen. We show that the sensing domain of KdpD interacts specifically with two membrane lipoproteins, LprJ (Rv1690) and LprF (Rv1368). Overexpression of lprF and lprJ alleles in mycobacterial kdpF-lacZ reporter strains enabled us to identify alleles that modulate kdpFABC expression. By exploiting the yeast three-hybrid system, we have found that the histidine kinase domain of KdpD forms ternary complexes with LprF and LprJ and the sensing module of KdpD. Our results establish a role for membrane proteins in the Kdp signalling pathway and suggest that LprF and LprJ function as accessory or ligand-binding proteins that communicate directly with the sensing domain of KdpD to modulate kdp expression.
authors.affiliation: Department of Immunology, Harvard School of Public Health, 665 Huntington Avenue, Boston, MA 02115, USA. asteyn@hsph.harvard.edu
authors.forename: Adrie J C
authors.initials: AJ
authors.lastname: Steyn
authors.forename: Joan
authors.initials: J
authors.lastname: Joseph
authors.forename: Barry R
authors.initials: BR
authors.lastname: Bloom
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D015870:Gene Expression; D005798:Genes, Bacterial; D008954:Models, Biological; D008958:Models, Molecular; D009169:Mycobacterium tuberculosis / Q000235:genetics* / Q000378:metabolism*; D010957:Plasmids / Q000235:genetics; D011188:Potassium / Q000378:metabolism; D011494:Protein Kinases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D001426:Bacterial Proteins; D011993:Recombinant Fusion Proteins; D011494:Protein Kinases; C075616:kdpD protein, Bacteria; D011188:Potassium