@article{b4fe017a48e846a1a2e5622c8bc3bf77,
title = "ppGpp Coordinates Nucleotide and Amino-Acid Synthesis in E. coli During Starvation",
abstract = "(p)ppGpp is a nucleotide messenger universally produced in bacteria following nutrient starvation. In E. coli, ppGpp inhibits purine nucleotide synthesis by targeting several different enzymes, but the physiological significance of their inhibition is unknown. Here, we report the structural basis of inhibition for one target, Gsk, the inosine-guanosine kinase. Gsk creates an unprecedented, allosteric binding pocket for ppGpp by restructuring terminal sequences, which restrains conformational dynamics necessary for catalysis. Guided by this structure, we generated a chromosomal mutation that abolishes Gsk regulation by ppGpp. This mutant strain accumulates abnormally high levels of purine nucleotides following amino-acid starvation, compromising cellular fitness. We demonstrate that this unrestricted increase in purine nucleotides is detrimental because it severely depletes pRpp and essential, pRpp-derived metabolites, including UTP, histidine, and tryptophan. Thus, our results reveal the significance of ppGpp's regulation of purine nucleotide synthesis and a critical mechanism by which E. coli coordinates biosynthetic processes during starvation.",
keywords = "Gsk, amino-acid synthesis, pRpp, ppGpp, purine nucleotide synthesis, stringent response",
author = "Boyuan Wang and Grant, {Robert A.} and Laub, {Michael T.}",
note = "Funding Information: This work was supported by fellowships from the Jane Coffin Childs Memorial Fund for Medical Research and NIH (K99GM135536) to B.W. and an NIH grant to M.T.L. (R01GM082899), who is also an Investigator of the Howard Hughes Medical Institute. This research made use of the Pilatus detector (RR029205) at the NE-CAT beamline 24-IDC (GM103403) of the Advanced Photon Source (DE-AC02-06CH11357). We thank the Whitehead Institute Metabolite Profiling Core Facility for measuring metabolite levels. Instrumentation resources from the Biophysical Instrumentation Facility for the Study of Complex Macromolecular Systems (NSF-0070319), the Structural Biology Core Facility, and the BioMicro Center in the Department of Biology at MIT are gratefully acknowledged. B.W. performed all experiments. R.A.G. helped with X-ray crystallography for structure determination. B.W. and M.T.L. designed experiments, analyzed data, prepared figures, and wrote the manuscript. The authors declare no competing interests. Funding Information: This work was supported by fellowships from the Jane Coffin Childs Memorial Fund for Medical Research and NIH ( K99GM135536 ) to B.W. and an NIH grant to M.T.L. ( R01GM082899 ), who is also an Investigator of the Howard Hughes Medical Institute . Publisher Copyright: {\textcopyright} 2020 Elsevier Inc.",
year = "2020",
month = oct,
day = "1",
doi = "10.1016/j.molcel.2020.08.005",
language = "English (US)",
volume = "80",
pages = "29--42.e10",
journal = "Molecular cell",
issn = "1097-2765",
publisher = "Cell Press",
number = "1",
}