Endogenous nitric oxide regulates the recovery of the radiation-resistant bacterium Deinococcus radiodurans from exposure to UV light.
Deinococcus radiodurans (Dr) withstands desiccation, reactive oxygen species, and doses of radiation that would be lethal to most organisms. Deletion of a gene encoding a homolog of mammalian nitric oxide synthase (NOS) severely compromises the recovery of Dr from ultraviolet (UV) radiation damage. The Deltanos defect can be complemented with recombinant NOS, rescued by exogenous nitric oxide (NO) and mimicked in the wild-type strain with an NO scavenging compound. UV radiation induces both upregulation of the nos gene and cellular NO production on similar time scales. Growth recovery does not depend on NO being present during UV irradiation, but rather can be manifested by NO addition hours after exposure. Surprisingly, nos deletion does not increase sensitivity to oxidative damage, and hydrogen peroxide does not induce nos expression. However, NOS-derived NO upregulates transcription of obgE, a gene involved in bacterial growth proliferation and stress response. Overexpression of the ObgE GTPase in the Deltanos background substantially alleviates the growth defect after radiation damage. Thus, NO acts as a signal for the transcriptional regulation of growth in D. radiodurans.
Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
Bhumit A
BA
Patel
Magali
M
Moreau
Joanne
J
Widom
Huan
H
Chen
Longfei
L
Yin
Yuejin
Y
Hua
Brian R
BR
Crane
D034301:Deinococcus / Q000254:growth & development / Q000378:metabolism* / Q000528:radiation effects*; D015971:Gene Expression Regulation, Enzymologic / Q000528:radiation effects; D050296:Microbial Viability / Q000528:radiation effects; D020559:Monomeric GTP-Binding Proteins / Q000235:genetics; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D014466:Ultraviolet Rays; D015854:Up-Regulation / Q000528:radiation effects
D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D020559:Monomeric GTP-Binding Proteins