title: The crystal structure of PknI from Mycobacterium tuberculosis shows an inactive, pseudokinase-like conformation.
abstract: Eukaryotic-like Ser/Thr protein kinases (ePKs) have been identified in many bacterial species, where they are known to mediate signalling mechanisms that share several features with their eukaryotic counterparts. In Mycobacterium tuberculosis, PknI is one of the 11 predicted ePKs and it has been related to bacterial virulence. In order to better understand the molecular basis of its role in mycobacterial signalling, we solved the crystal structure of the PknI cytoplasmic domain. We found that even though PknI possesses most conserved elements characteristic of Hanks-type kinases, it is degraded in several motifs that are essential for the ePKs catalytic activity. Most notably, PknI presents a remarkably short activation segment lacking a peptide-substrate binding site. Consistent with this observation and similar to earlier findings for eukaryotic pseudokinases, no kinase activity was detected for the catalytic domain of PknI, against different substrates and in various experimental conditions. Based on these results, we conclude that PknI may rely on unconventional mechanism(s) for kinase activity and/or it could play alternative role(s) in mycobacterial signalling.
  
  
  
  Atomic coordinates and structure factors for the catalytic domain of M. tuberculosis PknI are in the Protein Data Bank under the accession codes 5M06 (wild-type PknI + ADP), 5M07 (PknI_C20A), 5M08 (PknI_C20A_R136A) and 5M09 (PknI_C20A_R136N).
authors.affiliation: Unité de Microbiologie Structurale, Institut Pasteur, Paris Cedex, France.|CNRS UMR 3528 'Biologie structurale des processus cellulaires et maladies infectieuses', Institut Pasteur, Paris Cedex, France.|Sorbonne Paris Cité, Microbiologie Structurale, Université Paris Diderot, France.
authors.forename: María-Natalia
authors.initials: MN
authors.lastname: Lisa
authors.affiliation: Unité de Microbiologie Structurale, Institut Pasteur, Paris Cedex, France.|CNRS UMR 3528 'Biologie structurale des processus cellulaires et maladies infectieuses', Institut Pasteur, Paris Cedex, France.|Sorbonne Paris Cité, Microbiologie Structurale, Université Paris Diderot, France.
authors.forename: Tristan
authors.initials: T
authors.lastname: Wagner
authors.affiliation: Unité de Microbiologie Structurale, Institut Pasteur, Paris Cedex, France.|CNRS UMR 3528 'Biologie structurale des processus cellulaires et maladies infectieuses', Institut Pasteur, Paris Cedex, France.|Sorbonne Paris Cité, Microbiologie Structurale, Université Paris Diderot, France.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Alexandre
authors.affiliation: Unité de Microbiologie Structurale, Institut Pasteur, Paris Cedex, France.|CNRS UMR 3528 'Biologie structurale des processus cellulaires et maladies infectieuses', Institut Pasteur, Paris Cedex, France.|Sorbonne Paris Cité, Microbiologie Structurale, Université Paris Diderot, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Barilone
authors.affiliation: CNRS UMR 3528 'Biologie structurale des processus cellulaires et maladies infectieuses', Institut Pasteur, Paris Cedex, France.|Plateforme de Biophysique Moléculaire, Institut Pasteur, Paris Cedex, France.
authors.forename: Bertrand
authors.initials: B
authors.lastname: Raynal
authors.affiliation: Unité de Microbiologie Structurale, Institut Pasteur, Paris Cedex, France.|CNRS UMR 3528 'Biologie structurale des processus cellulaires et maladies infectieuses', Institut Pasteur, Paris Cedex, France.|Sorbonne Paris Cité, Microbiologie Structurale, Université Paris Diderot, France.
authors.forename: Pedro M
authors.initials: PM
authors.lastname: Alzari
authors.affiliation: Unité de Microbiologie Structurale, Institut Pasteur, Paris Cedex, France.|CNRS UMR 3528 'Biologie structurale des processus cellulaires et maladies infectieuses', Institut Pasteur, Paris Cedex, France.|Sorbonne Paris Cité, Microbiologie Structurale, Université Paris Diderot, France.
authors.forename: Marco
authors.identifier: 0000-0002-8887-6917
authors.initials: M
authors.lastname: Bellinzoni
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D003001:Cloning, Molecular; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D008958:Models, Molecular; D009169:Mycobacterium tuberculosis / Q000737:chemistry* / Q000201:enzymology; D011485:Protein Binding; D000072756:Protein Conformation, alpha-Helical; D000072757:Protein Conformation, beta-Strand; D054730:Protein Interaction Domains and Motifs; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins; D017346:Protein Serine-Threonine Kinases
keywords: Ser/Thr kinase; X-ray crystallography; activation segment; signal transduction