Cellular and Molecular Life Sciences

, Volume 71, Issue 15, pp 2963–2973 | Cite as

Glutamine deprivation initiates reversible assembly of mammalian rods and rings

  • S. John Calise
  • Wendy C. Carcamo
  • Claire Krueger
  • Joyce D. Yin
  • Daniel L. Purich
  • Edward K. L. Chan
Research Article


Rods and rings (RR) are protein assemblies composed of cytidine triphosphate synthetase type 1 (CTPS1) and inosine monophosphate dehydrogenase type 2 (IMPDH2), key enzymes in CTP and GTP biosynthesis. Small-molecule inhibitors of CTPS1 or IMPDH2 induce RR assembly in various cancer cell lines within 15 min to hours. Since glutamine is an essential amide nitrogen donor in these nucleotide biosynthetic pathways, glutamine deprivation was examined to determine whether it leads to RR formation. HeLa cells cultured in normal conditions did not show RR, but after culturing in media lacking glutamine, short rods (<2 μm) assembled after 24 h, and longer rods (>5 μm) formed after 48 h. Upon supplementation with glutamine or guanosine, these RR underwent almost complete disassembly within 15 min. Inhibition of glutamine synthetase with methionine sulfoximine also increased RR assembly in cells deprived of glutamine. Taken together, our data support the hypothesis that CTP/GTP biosynthetic enzymes polymerize to form RR in response to a decreased intracellular level of glutamine. We speculate that rod and ring formation is an adaptive metabolic response linked to disruption of glutamine homeostasis.


Cytidine triphosphate synthetase Glutamine Inosine monophosphate dehydrogenase Rods and rings 



Rods and rings


Cytidine triphosphate synthetase


Inosine monophosphate dehydrogenase




Cytidine triphosphate


Guanine monophosphate


Mycophenolic acid


Fetal bovine serum


Guanosine triphosphate


Uridine triphosphate


Messenger RNA



We thank Thuy Nguyen and Dania Saleem for their technical assistance with ribonucleoside treatment and time-point analysis of RR disassembly by glutamine.

Supplementary material

18_2014_1567_MOESM1_ESM.jpg (383 kb)
Supplementary material 1 (JPEG 382 kb)
18_2014_1567_MOESM2_ESM.pdf (1.1 mb)
Supplementary material 2 (PDF 1138 kb)


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Copyright information

© Springer Basel 2014

Authors and Affiliations

  • S. John Calise
    • 1
  • Wendy C. Carcamo
    • 1
  • Claire Krueger
    • 1
  • Joyce D. Yin
    • 1
  • Daniel L. Purich
    • 2
  • Edward K. L. Chan
    • 1
  1. 1.Department of Oral BiologyUniversity of FloridaGainesvilleUSA
  2. 2.Department of Biochemistry and Molecular BiologyUniversity of FloridaGainesvilleUSA

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