Key residues in Mycobacterium tuberculosis protein kinase G play a role in regulating kinase activity and survival in the host

Divya Tiwari, Rajnish Kumar Singh, Kasturi Goswami, Sunil Kumar Verma, Balaji Prakash, Vinay Kumar Nandicoori

Research output: Contribution to journalArticle

43 Citations (Scopus)

Abstract

Protein kinase G (PknG) in Mycobacterium tuberculosis has been shown to modulate phagosome-lysosome fusion. The protein has three distinct domains, an N-terminal Trx domain, a kinase domain, and a C-terminal TPR domain. The present study extensively analyzes the roles of these domains in regulating PknG kinase activity and function. We find that the kinase domain ofPknGby itself is inactive, signifying the importance of the flanking domains. Although the deletion of the Trx domain severely impacts the activity of the protein, the C-terminal region also contributes significantly in regulating the activity of the kinase. Apart from this, PknG kinase activity is dependent on the presence of threonine 309 in the p + 1 loop of the activation segment. Mutating the conserved cysteine residues in the Trx motifs makes PknG refractory to changes in the redox environment. In vitro experiments identify threonine 63 as the major phosphorylation site of the protein. Importantly, we find that this is the only site in the protein that is phosphorylated in vivo. Macrophage infection studies reveal that the first 73 residues, the Trx motifs, and the threonine 63 residue are independently essential for modulating PknG-mediated survival of mycobacteria in its host. We have extended these studies to investigate the role of PknG and PknG mutants in the pathogenesis of mycobacteria in mice. Our results reinforce the findings from the macrophage infection experiments, and for the first time demonstrate that the expression of PknG in non-pathogenic mycobacteria allows the continued existence of these bacteria in host tissues.

Original languageEnglish (US)
Pages (from-to)27467-27479
Number of pages13
JournalJournal of Biological Chemistry
Volume284
Issue number40
DOIs
StatePublished - Oct 2 2009
Externally publishedYes

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Cyclic GMP-Dependent Protein Kinases
Phosphotransferases
Threonine
Mycobacterium
Macrophages
Mycobacterium tuberculosis protein kinase G
Phagosomes
Proteins
Phosphorylation
Protein C
Lysosomes
Infection
GTP-Binding Proteins
Oxidation-Reduction
Cysteine
Refractory materials
Bacteria
Fusion reactions
Experiments
Chemical activation

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology
  • Medicine(all)

Cite this

Key residues in Mycobacterium tuberculosis protein kinase G play a role in regulating kinase activity and survival in the host. / Tiwari, Divya; Singh, Rajnish Kumar; Goswami, Kasturi; Verma, Sunil Kumar; Prakash, Balaji; Nandicoori, Vinay Kumar.

In: Journal of Biological Chemistry, Vol. 284, No. 40, 02.10.2009, p. 27467-27479.

Research output: Contribution to journalArticle

Tiwari, Divya ; Singh, Rajnish Kumar ; Goswami, Kasturi ; Verma, Sunil Kumar ; Prakash, Balaji ; Nandicoori, Vinay Kumar. / Key residues in Mycobacterium tuberculosis protein kinase G play a role in regulating kinase activity and survival in the host. In: Journal of Biological Chemistry. 2009 ; Vol. 284, No. 40. pp. 27467-27479.
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