Abstract
Work demonstrating the operation of a photorespiratory N cycle in Chlamydomonas is described. NH3 release by this process is light dependent, sensitive to changes in pO2 and pCO2, and abolished by a photosystem II inhibitor. Evidence is presented which shows that this NH3 derives its N from protein rather than from freshly synthesised glutamate. Protein turnover is shown to provide amino-N at a rate sufficient to account for the highest photorespiratory N excretion observed suggesting that changes in excretion can be accounted for by increased catabolism of normally recirculating amino acids. It is equally possible however that a direct link between photorespiration and protein turnover exists, increased NH3 excretion resulting from enhanced protein turnover. The data suggest that if similar mechanisms operate in higher plants, previous estimates of the amount of N recycled in photorespiration may have been too high.
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Abbreviations
- GS:
-
glutamine synthetase
- PMSF:
-
phenyl methyl sulfonyl fluoride
- MSO:
-
L-methionine-DL-sulfoximine
- DCMU:
-
3-(3,4-dichlorophenyl)-1,1-dimethyl urea
References
Cooke, R.J., Oliver, J., Davies, D.D., (1979) Stress and protein turnover in Lemna minor. Plant Physiol. 64, 1103–1109
Cullimore, J.V. Sims, A.P. (1980a) Occurrence of two forms of glutamate synthase in Chlamydomonas reinhardii. Phytochemistry, in press
Cullimore, J. V., Sims, A.P. (1980b) Pathway of ammonia assimilation in illuminated and darkened Chlamydomonas reinhardii. Phytochemistry in press
Ferguson, A.R., Sims, A.P. (1971) Inactivation in vivo of glutamine synthetase and NAD specific glutamate dehydrogenase: its role in the regulation of glutamine synthesis in yeasts. J. Gen. Microbiol. 69, 423–427
Humphrey, T.J., Davies, D.D. (1976) A sensitive method for measuring protein turnover based on the measurement of 2 3H-labelled amino acids in protein. Biochem. J. 156, 561–568
Keys, A.L., Bird, I.F., Cornelius, M.J., Lea, P.J., Wallsgrove, R.M., Miflin, B.J. (1978) Photorespiratory nitrogen cycle. Nature (London) 275, 741–743
Lowry, O.H., Rosebrough, N.J., Farr, A.L., Randall, R.J. (1951) Protein measurement with the Folin phenol reagent. J. Biol. Chem. 193, 265–275
Miflin, B.J., Lea, P.J. (1980) Ammonia assimilation. In: The biochemistry of plants, vol. V, pp 169–202, Stumpf, P.K. and Conn, E.E. eds. Academic Press, New York
Sims, A.P., Ferguson, A.R. (1974) The regulation of glutamine metabolism in Candida utilis: Studies with 15NH3 to measure in vivo rates of glutamine synthesis. J. Gen. Microbiol. 80, 143–158
Somerville, C.R., Ogren, W.L. (1980a) Photorespiration mutants of Arabidopsis thaliana deficient in serine-glyoxylate aminotransferase activity. Proc. Natl. Acad. Sci. (USA), 77, 2684–2687
Somerville, C.R., Ogren, W.L. (1980b) Photosynthesis is inhibited in mutants of Arabidopsis deficient in glutamate synthase (GOGAT) activity. Nature (London) 286, 267–269
Thacker, A., Syrett, P.J. (1972) The assimilation of nitrate and ammonium by Chlamydomonas reinhardii. New Phytol. 71, 423–433
Tyler, B. (1978) Regulation of the assimilation of nitrogen compounds. Annu. Rev. Biochem. 47, 1127–1162
Weatherburn, M.W. (1967) Phenol hypochlorite reaction for determination of ammonia. Anal. Chem. 39, 971–974
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Cullimore, J.V., Sims, A.P. An association between photorespiration and protein catabolism: Studies with Chlamydomonas . Planta 150, 392–396 (1980). https://doi.org/10.1007/BF00390175
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DOI: https://doi.org/10.1007/BF00390175