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Proteomics of Nitrogen Remobilization in Poplar Bark

Author:
Nazrul Islam, Gen Li, Wesley M. Garrett, Rongshuang Lin, Ganesh Sriram, Bret Cooper, Gary D. Coleman
Source:
Journal of proteome research 2015 v.14 no.2 pp. 1112-1126
ISSN:
1535-3893
Subject:
metabolism, proteome, serine, autumn, nitrogen, nitrogen cycle, shoots, spring, carboxypeptidases, trees, parenchyma (plant tissue), seasonal variation, wood anatomy, proteomics, aspartic proteinases, bark, storage proteins, enzyme activity, leaves, cysteine proteinases
Abstract:
Seasonal nitrogen (N) cycling in temperate deciduous trees involves the accumulation of bark storage proteins (BSPs) in phloem parenchyma and xylem ray cells. BSPs are anabolized using recycled N during autumn leaf senescence and later become a source of N during spring shoot growth as they are catabolized. Little is known about the catabolic processes involved in remobilization and reutilization of N from BSPs in trees. In this study, we used multidimensional protein identification technology (MudPIT) and spectral counting to identify protein changes that occur in the bark during BSP catabolism. A total of 4,178 proteins were identified from bark prior to and during BSP catabolism. The majority (62%) of the proteins were found during BSP catabolism, indicating extensive remodeling of the proteome during renewed shoot growth and N remobilization. Among these proteins were 30 proteases, the relative abundances of which increased during BSP catabolism. These proteases spanned a range of families including members of the papain-like cysteine proteases, serine carboxypeptidases, and aspartyl proteases. These data identify, for the first time, candidate proteases that could potentially provide hydrolase activity required for N remobilization from BSPs and provide the foundation for research to advance our knowledge of poplar N cycling.
Agid:
61531
Handle:
10113/61531