title: Phosphorylation regulates mycobacterial proteasome.
abstract: Mycobacterium tuberculosis possesses a proteasome system that is required for the microbe to resist elimination by the host immune system. Despite the importance of the proteasome in the pathogenesis of tuberculosis, the molecular mechanisms by which proteasome activity is controlled remain largely unknown. Here, we demonstrate that the α-subunit (PrcA) of the M. tuberculosis proteasome is phosphorylated by the PknB kinase at three threonine residues (T84, T202, and T178) in a sequential manner. Furthermore, the proteasome with phosphorylated PrcA enhances the degradation of Ino1, a known proteasomal substrate, suggesting that PknB regulates the proteolytic activity of the proteasome. Previous studies showed that depletion of the proteasome and the proteasome-associated proteins decreases resistance to reactive nitrogen intermediates (RNIs) but increases resistance to hydrogen peroxide (H2O2). Here we show that PknA phosphorylation of unprocessed proteasome β-subunit (pre-PrcB) and α-subunit reduces the assembly of the proteasome complex and thereby enhances the mycobacterial resistance to H2O2 and that H2O2 stress diminishes the formation of the proteasome complex in a PknA-dependent manner. These findings indicate that phosphorylation of the M. tuberculosis proteasome not only modulates proteolytic activity of the proteasome, but also affects the proteasome complex formation contributing to the survival of M. tuberculosis under oxidative stress conditions.
authors.affiliation: Department of Biological Science, Wayne State University, Detroit, MI, 48202, USA.
authors.forename: Tripti
authors.initials: T
authors.lastname: Anandan
authors.forename: Jaeil
authors.initials: J
authors.lastname: Han
authors.forename: Heather
authors.initials: H
authors.lastname: Baun
authors.forename: Seeta
authors.initials: S
authors.lastname: Nyayapathy
authors.forename: Jacob T
authors.initials: JT
authors.lastname: Brown
authors.forename: Rebekah L
authors.initials: RL
authors.lastname: Dial
authors.forename: Juan A
authors.initials: JA
authors.lastname: Moltalvo
authors.forename: Min-Seon
authors.initials: MS
authors.lastname: Kim
authors.forename: Seung Hwan
authors.initials: SH
authors.lastname: Yang
authors.forename: Donald R
authors.initials: DR
authors.lastname: Ronning
authors.forename: Robert N
authors.initials: RN
authors.lastname: Husson
authors.forename: Joowon
authors.initials: J
authors.lastname: Suh
authors.forename: Choong-Min
authors.initials: CM
authors.lastname: Kang
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D006861:Hydrogen Peroxide / Q000378:metabolism; D009169:Mycobacterium tuberculosis / Q000201:enzymology* / Q000378:metabolism*; D010766:Phosphorylation; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D059748:Proteolysis; D013381:Subtilisins / Q000378:metabolism*; D013912:Threonine / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; C102527:PrcA protein, bacteria; D013912:Threonine; D006861:Hydrogen Peroxide; C475060:PknB protein, Mycobacterium tuberculosis; D017346:Protein Serine-Threonine Kinases; D013381:Subtilisins; D046988:Proteasome Endopeptidase Complex