Adenylylation of mycobacterial Glnk (PII) protein is induced by nitrogen limitation.
PII proteins are pivotal regulators of nitrogen metabolism in most prokaryotes, controlling the activities of many targets, including nitrogen assimilation enzymes, two component regulatory systems and ammonium transport proteins. Escherichia coli contains two PII-like proteins, PII (product of glnB) and GlnK, both of which are uridylylated under nitrogen limitation at a conserved Tyrosine-51 residue by GlnD (a uridylyl transferase). PII-uridylylation in E. coli controls glutamine synthetase (GS) adenylylation by GlnE and mediates the NtrB/C transcriptomic response. Mycobacteria contain only one PII protein (GlnK) which in environmental Actinomycetales is adenylylated by GlnD under nitrogen limitation. However in mycobacteria, neither the type of GlnK (PII) covalent modification nor its precise role under nitrogen limitation is known. In this study, we used LC-Tandem MS to analyse the modification state of mycobacterial GlnK (PII), and demonstrate that during nitrogen limitation GlnK from both non-pathogenic Mycobacterium smegmatis and pathogenic Mycobacterium tuberculosis is adenylylated at the Tyrosine-51 residue; we also show that GlnD is the adenylyl transferase enzyme responsible. Further analysis shows that in contrast to E. coli, GlnK (PII) adenylylation in M. tuberculosis does not regulate GS adenylylation, nor does it mediate the transcriptomic response to nitrogen limitation.
MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Exhibition Road, South Kensington, London SW7 2AZ, UK.
Kerstin J
KJ
Williams
Mark H
MH
Bennett
Geraint R
GR
Barton
Victoria A
VA
Jenkins
Brian D
BD
Robertson
D001426:Bacterial Proteins / Q000378:metabolism* / Q000502:physiology; D002474:Cell-Free System / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D005798:Genes, Bacterial; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism; D020102:Mycobacterium smegmatis / Q000235:genetics / Q000378:metabolism*; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000378:metabolism*; D009584:Nitrogen / Q000172:deficiency* / Q000378:metabolism; D051922:PII Nitrogen Regulatory Proteins / Q000378:metabolism* / Q000502:physiology; D011499:Protein Processing, Post-Translational; D013312:Stress, Physiological / Q000235:genetics / Q000502:physiology; D053719:Tandem Mass Spectrometry / Q000379:methods
D001426:Bacterial Proteins; D051922:PII Nitrogen Regulatory Proteins; D005974:Glutamate-Ammonia Ligase; D009584:Nitrogen