An osmoregulated dipeptide in stressed Rhizobium meliloti.
One common mechanism of cellular adaptation to osmotic stress is the accumulation of organic solutes in the cytosol. We have used natural-abundance 13C nuclear magnetic resonance to identify all organic solutes that accumulate to significant levels in Rhizobium meliloti. Our studies led to the discovery of a new dipeptide, N-acetylglutaminylglutamine amide (NAGGN), which is accumulated during osmotic stress. Only rarely have peptides been shown to function in bacteria, and furthermore, this is the first example of a peptide playing a role in osmoregulation. Evidence for the biological role of NAGGN in osmotic-stress protection is presented.
Plant Growth Laboratory, University of California, Davis 95616.
L T
LT
Smith
G M
GM
Smith
D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004151:Dipeptides / Q000302:isolation & purification / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D013058:Mass Spectrometry; D012231:Rhizobium / Q000502:physiology*; D014882:Water-Electrolyte Balance
D004151:Dipeptides; C060785:N-acetylglutaminylglutamine amide