title: Interaction of Mycobacterium tuberculosis elongation factor Tu with GTP is regulated by phosphorylation.
abstract: During protein synthesis, translation elongation factor Tu (Ef-Tu) is responsible for the selection and binding of the cognate aminoacyl-tRNA to the acceptor site on the ribosome. The activity of Ef-Tu is dependent on its interaction with GTP. Posttranslational modifications, such as phosphorylation, are known to regulate the activity of Ef-Tu in several prokaryotes. Although a study of the Mycobacterium tuberculosis phosphoproteome showed Ef-Tu to be phosphorylated, the role of phosphorylation in the regulation of Ef-Tu has not been studied. In this report, we show that phosphorylation of M. tuberculosis Ef-Tu (MtbEf-Tu) by PknB reduced its interaction with GTP, suggesting a concomitant reduction in the level of protein synthesis. Overexpression of PknB in Mycobacterium smegmatis indeed reduced the level of protein synthesis. MtbEf-Tu was found to be phosphorylated by PknB on multiple sites, including Thr118, which is required for optimal activity of the protein. We found that kirromycin, an Ef-Tu-specific antibiotic, had a significant effect on the nucleotide binding of unphosphorylated MtbEf-Tu but not on the phosphorylated protein. Our results show that the modulation of the MtbEf-Tu-GTP interaction by phosphorylation can have an impact on cellular protein synthesis and growth. These results also suggest that phosphorylation can change the sensitivity of the protein to the specific inhibitors. Thus, the efficacy of an inhibitor can also depend on the posttranslational modification(s) of the target and should be considered during the development of the molecule.
authors.affiliation: Institute of Genomics and Integrative Biology (CSIR), Mall Road, Delhi 110007, India.
authors.forename: Andaleeb
authors.initials: A
authors.lastname: Sajid
authors.forename: Gunjan
authors.initials: G
authors.lastname: Arora
authors.forename: Meetu
authors.initials: M
authors.lastname: Gupta
authors.forename: Anshika
authors.initials: A
authors.lastname: Singhal
authors.forename: Kausik
authors.initials: K
authors.lastname: Chakraborty
authors.forename: Vinay Kumar
authors.initials: VK
authors.lastname: Nandicoori
authors.forename: Yogendra
authors.initials: Y
authors.lastname: Singh
mesh_terms: D015180:Electrophoresis, Gel, Two-Dimensional; D006160:Guanosine Triphosphate / Q000378:metabolism*; D015151:Immunoblotting; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D010444:Peptide Elongation Factor Tu / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D010769:Phosphothreonine / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases; D011728:Pyridones / Q000494:pharmacology
chemical_list: D010750:Phosphoproteins; D011728:Pyridones; D010769:Phosphothreonine; D006160:Guanosine Triphosphate; C475060:PknB protein, Mycobacterium tuberculosis; D017346:Protein Serine-Threonine Kinases; D010444:Peptide Elongation Factor Tu; C008536:mocimycin