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The 15 N isotope effect in Escherichia coli : A neutron can make the difference
Author(s) -
Filiou Michaela D.,
Varadarajulu Jeeva,
Teplytska Larysa,
Reckow Stefan,
Maccarrone Giuseppina,
Turck Christoph W.
Publication year - 2012
Publication title -
proteomics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.26
H-Index - 167
eISSN - 1615-9861
pISSN - 1615-9853
DOI - 10.1002/pmic.201200209
Subject(s) - metabolite , escherichia coli , isotope , stable isotope ratio , stable isotope labeling by amino acids in cell culture , proteome , chemistry , bacteria , radiochemistry , biology , proteomics , biochemistry , gene , genetics , physics , quantum mechanics
Several techniques based on stable isotope labeling are used for quantitative MS. These include stable isotope metabolic labeling methods for cells in culture as well as live organisms with the assumption that the stable isotope has no effect on the proteome. Here, we investigate the 15 N isotope effect on Escherichia coli cultures that were grown in either unlabeled ( 14 N) or 15 N‐labeled media by LC‐ESI‐MS/MS‐based relative protein quantification. Consistent protein expression level differences and altered growth rates were observed between 14 N and 15 N‐labeled cultures. Furthermore, targeted metabolite analyses revealed altered metabolite levels between 14 N and 15 N‐labeled bacteria. Our data demonstrate for the first time that the introduction of the 15 N isotope affects protein and metabolite levels in E. coli and underline the importance of implementing controls for unbiased protein quantification using stable isotope labeling techniques.