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Title: Extensive Turnover of Compatible Solutes in Cyanobacteria Revealed by Deuterium Oxide (D 2 O) Stable Isotope Probing

In diverse environments on a global scale cyanobacteria are important primary producers of organic matter. Moreover, while mechanisms of CO 2 fixation are well understood, the distribution of the flow of fixed organic carbon within individual cells and complex microbial communities is less well characterized. To obtain a general overview of metabolism, we describe the use of deuterium oxide (D 2O) to measure deuterium incorporation into the intracellular metabolites of two physiologically diverse cyanobacteria: a terrestrial filamentous strain (Microcoleus vaginatus PCC 9802) and a euryhaline unicellular strain (Synechococcus sp. PCC 7002). D 2O was added to the growth medium during different phases of the diel cycle. Incorporation of deuterium into metabolites at nonlabile positions, an indicator of metabolite turnover, was assessed using liquid chromatography mass spectrometry. Expectedly, large differences in turnover among metabolites were observed. Some metabolites, such as fatty acids, did not show significant turnover over 12–24 h time periods but did turn over during longer time periods. Unexpectedly, metabolites commonly regarded to act as compatible solutes, including glutamate, glucosylglycerol, and a dihexose, showed extensive turnover compared to most other metabolites already after 12 h, but only during the light phase in the cycle. We observed extensive turnover andmore » found it surprising considering the conventional view on compatible solutes as biosynthetic end points given the relatively slow growth and constant osmotic conditions. Our suggests the possibility of a metabolic sink for some compatible solutes (e.g., into glycogen) that allows for rapid modulation of intracellular osmolarity. To investigate this, uniformly 13C-labeled Synechococcus sp. PCC 7002 were exposed to 12C glucosylglycerol. Following metabolite extraction, amylase treatment of methanol-insoluble polymers revealed 12C labeling of glycogen. Overall, our work shows that D 2O probing is a powerful method for analysis of cyanobacterial metabolism including discovery of novel metabolic processes.« less
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [3] ; ORCiD logo [4]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Environmental Genomics and Systems Biology Division
  2. Univ. of California, San Diego, CA (United States). Center for Circadian Biology and Division of Biological Sciences
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Environmental Genomics and Systems Biology Division; Arizona State Univ., Tempe, AZ (United States). School of Life Sciences
  4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Environmental Genomics and Systems Biology Division; Arizona State Univ., Tempe, AZ (United States). School of Life Sciences; USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States)
Publication Date:
Grant/Contract Number:
AC02-05CH11231
Type:
Published Article
Journal Name:
ACS Chemical Biology
Additional Journal Information:
Journal Volume: 12; Journal Issue: 3; Journal ID: ISSN 1554-8929
Publisher:
American Chemical Society (ACS)
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 59 BASIC BIOLOGICAL SCIENCES
OSTI Identifier:
1347258
Alternate Identifier(s):
OSTI ID: 1347362