title: Septal localization of the Mycobacterium tuberculosis MtrB sensor kinase promotes MtrA regulon expression.
abstract: The mechanisms responsible for activation of the MtrAB two-component regulatory signal transduction system, which includes sensor kinase MtrB and response regulator MtrA, are unknown. Here, we show that an MtrB-GFP fusion protein localized to the cell membrane, the septa, and the poles in Mycobacterium tuberculosis and Mycobacterium smegmatis. This localization was independent of MtrB phosphorylation status but dependent upon the assembly of FtsZ, the initiator of cell division. The M. smegmatis mtrB mutant was filamentous, defective for cell division, and contained lysozyme-sensitive cell walls. The mtrB phenotype was complemented by either production of MtrB protein competent for phosphorylation or overproduction of MtrA(Y102C) and MtrA(D13A) mutant proteins exhibiting altered phosphorylation potential, indicating that either MtrB phosphorylation or MtrB independent expression of MtrA regulon genes, including those involved in cell wall processing, are necessary for regulated cell division. In partial support of this observation, we found that the essential cell wall hydrolase ripA is an MtrA target and that the expression of bona fide MtrA targets ripA, fbpB, and dnaA were compromised in the mtrB mutant and partially rescued upon MtrA(Y102C) and MtrA(D13A) overproduction. MtrB septal assembly was compromised upon FtsZ depletion and exposure of cells to mitomycin C, a DNA damaging agent, which interferes with FtsZ ring assembly. Expression of MtrA targets was also compromised under the above conditions, indicating that MtrB septal localization and MtrA regulon expression are linked. We propose that MtrB septal association is a necessary feature of MtrB activation that promotes MtrA phosphorylation and MtrA regulon expression.
authors.affiliation: Biomedical Research, The University of Texas Health Science Center, Tyler, Texas 75708-3154, USA.
authors.forename: Renata
authors.initials: R
authors.lastname: Plocinska
authors.forename: Gorla
authors.initials: G
authors.lastname: Purushotham
authors.forename: Krishna
authors.initials: K
authors.lastname: Sarva
authors.forename: Indumathi S
authors.initials: IS
authors.lastname: Vadrevu
authors.forename: Emmanuel V P
authors.initials: EV
authors.lastname: Pandeeti
authors.forename: Naresh
authors.initials: N
authors.lastname: Arora
authors.forename: Przemyslaw
authors.initials: P
authors.lastname: Plocinski
authors.forename: Murty V
authors.initials: MV
authors.lastname: Madiraju
authors.forename: Malini
authors.initials: M
authors.lastname: Rajagopalan
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D015153:Blotting, Western; D002455:Cell Division; D002462:Cell Membrane / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D009154:Mutation; D020102:Mycobacterium smegmatis / Q000235:genetics / Q000378:metabolism; D009169:Mycobacterium tuberculosis / Q000235:genetics* / Q000378:metabolism; D010766:Phosphorylation; D010770:Phosphotransferases / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D018085:Regulon / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D003598:Cytoskeletal Proteins; C071525:FtsZ protein, Bacteria; C100938:MtrA protein, Bacteria; C079092:MtrB protein, Bacteria; D016601:RNA-Binding Proteins; D014157:Transcription Factors; D049452:Green Fluorescent Proteins; D010770:Phosphotransferases