1887

Abstract

sp. ATCC 51142 is an aerobic N-fixing and hydrogen-producing cyanobacterium. Isotopomer analysis of its amino acids revealed an identical labelling profile for leucine and isoleucine when 51142 was grown mixotrophically using 2-C-labelled glycerol as the main carbon source. This indicated that 51142 employs the atypical alternative citramalate pathway for isoleucine synthesis, with pyruvate and acetyl-CoA as precursors. Utilization of the citramalate pathway was confirmed by an enzyme assay and LC-MS/MS analysis. Furthermore, the genome sequence of 51142 shows that the gene encoding the key enzyme (threonine ammonia-lyase) in the normal isoleucine pathway is missing. Instead, the cce_0248 gene in 51142 exhibits 53 % identity to the gene encoding citramalate synthase (CimA, GSU1798) from . Reverse-transcription PCR indicated that the cce_0248 gene is expressed and its transcriptional level is lower in medium with isoleucine than in isoleucine-free medium. Additionally, a search for citramalate synthase and threonine ammonia-lyase implies that this alternative isoleucine synthesis pathway may be present in other cyanobacteria, such as and . This suggests that the pathway is more widespread than originally thought, as previous identifications of the citramalate pathway are limited to mostly anaerobic bacteria or archaea. Furthermore, this discovery opens the possibility that such autrotrophic micro-organisms may be engineered for robust butanol and propanol production from 2-ketobutyrate, which is an intermediate in the isoleucine biosynthesis pathway.

Loading

Article metrics loading...

/content/journal/micro/10.1099/mic.0.031799-0
2010-02-01
2020-07-05
Loading full text...

Full text loading...

/deliver/fulltext/micro/156/2/596.html?itemId=/content/journal/micro/10.1099/mic.0.031799-0&mimeType=html&fmt=ahah

References

  1. Atsumi S., Liao J. C.. 2008; Directed evolution of Methanococcus jannaschii citramalate synthase for biosynthesis of 1-propanol and 1-butanol by Escherichia coli. Appl Environ Microbiol74:7802–7808
    [Google Scholar]
  2. Charon N. W., Johnson R. C., Peterson D.. 1974; Amino acid biosynthesis in the spirochete Leptospira: evidence for a novel pathway of isoleucine biosynthesis. J Bacteriol117:203–211
    [Google Scholar]
  3. Colón-López M. S., Sherman L. A.. 1998; Transcriptional and translational regulation of photosystem I and II genes in light-dark- and continuous-light-grown cultures of the unicellular cyanobacterium Cyanothece sp. strain ATCC 51142. J Bacteriol180:519–526
    [Google Scholar]
  4. Eikmanns B., Linder D., Thauer R. K.. 1983; Unusual pathway of isoleucine biosynthesis in Methanobacterium thermoautotrophicum. Arch Microbiol136:111–113
    [Google Scholar]
  5. Feng X., Mouttaki H., Lin L., Huang R., Wu B., Hemme C. L., He Z., Zhang B., Hicks L. M.. other authors 2009; Characterization of the central metabolic pathways in Thermoanaerobacter sp. X514 via isotopomer-assisted metabolite analysis. Appl Environ Microbiol75:5001–5008
    [Google Scholar]
  6. Heinig K., Henion J.. 1999; Fast liquid chromatographic-mass spectrometric determination of pharmaceutical compounds. J Chromatogr B Biomed Sci Appl732:445–458
    [Google Scholar]
  7. Howell D. M., Xu H. M., White R. H.. 1999; ( R)-Citramalate synthase in methanogenic archaea. J Bacteriol181:331–333
    [Google Scholar]
  8. Jahn U., Huber H., Eisenreich W., Hugler M., Fuchs G.. 2007; Insights into the autotrophic CO2 fixation pathway of the archaeon Ignicoccus hospitalis: comprehensive analysis of the central carbon metabolism. J Bacteriol189:4108–4119
    [Google Scholar]
  9. Johnson D. R., Lee P. K. H., Holmes V. F., Fortin A. C., Alvarez-Cohen L.. 2005; Transcriptional expression of the tceA gene in a Dehalococcoides-containing microbial enrichment. Appl Environ Microbiol71:7145–7151
    [Google Scholar]
  10. Kisumi M., Komatsubara S., Chibata I.. 1977; Pathway for isoleucine formation form pyruvate by leucine biosynthetic enzymes in leucine-accumulating isoleucine revertants of Serratia marcescens. J Biochem82:95–103
    [Google Scholar]
  11. Risso C., Van Dien S. J., Orloff A., Lovley D. R., Coppi M. V.. 2008; Elucidation of an alternate isoleucine biosynthesis pathway in Geobacter sulfurreducens. J Bacteriol190:2266–2274
    [Google Scholar]
  12. Schäfer S., Paalme T., Vilu R., Fuchs G.. 1989; 13C-NMR study of acetate assimilation in Thermoproteus neutrophilus. Eur J Biochem186:695–700
    [Google Scholar]
  13. Shastri A. A., Morgan J. A.. 2007; A transient isotopic labeling methodology for 13C metabolic flux analysis of photoautotrophic microorganisms. Phytochemistry68:2302–2312
    [Google Scholar]
  14. Stöckel J., Welsh E. A., Liberton M., Kunnvakkam R., Aurora R., Pakrasi H. B.. 2008; Global transcriptomic analysis of Cyanothece 51142 reveals robust diurnal oscillation of central metabolic processes. Proc Natl Acad Sci U S A105:6156–6161
    [Google Scholar]
  15. Tang Y. J., Chakraborty R., Martin H. G., Chu J., Hazen T. C., Keasling J. D.. 2007; Flux analysis of central metabolic pathways in Geobacter metallireducens during reduction of soluble Fe(III)-NTA. Appl Environ Microbiol73:3859–3864
    [Google Scholar]
  16. Tang Y. J., Martin H. G., Myers S., Rodriguez S., Baidoo E. E., Keasling J. D.. 2009a; Advances in analysis of microbial metabolic fluxes via 13C isotopic labeling. Mass Spectrom Rev28:362–375
    [Google Scholar]
  17. Tang Y. J., Sapra R., Joyner D., Hazen T. C., Myers S., Reichmuth D., Blanch H., Keasling J. D.. 2009b; Analysis of metabolic pathways and fluxes in a newly discovered thermophilic and ethanol-tolerant Geobacillus strain. Biotechnol Bioeng102:1377–1386
    [Google Scholar]
  18. Tang Y. J., Yi S., Zhuang W.-Q., Zinder S. H., Keasling J. D., Alvarez-Cohen L.. 2009c; Investigation of carbon metabolism in “ Dehalococcoides ethenogenes” strain 195 via isotopic and transcriptomic analyses. J Bacteriol191:5224–5231
    [Google Scholar]
  19. Toepel J., Welsh E., Summerfield T. C., Pakrasi H. B., Sherman L. A.. 2008; Differential transcriptional analysis of the cyanobacterium Cyanothece sp strain ATCC 51142 during light-dark and continuous-light growth. J Bacteriol190:3904–3913
    [Google Scholar]
  20. Wahl S. A., Dauner M., Wiechert W.. 2004; New tools for mass isotopomer data evaluation in 13C flux analysis: mass isotope correction, data consistency checking, and precursor relationships. Biotechnol Bioeng85:259–268
    [Google Scholar]
  21. Welsh E. A., Liberton M., Stöckel J., Loh T., Elvitigala T., Wang C., Wollam A., Fulton R. S., Clifton S. W.. other authors 2008; The genome of Cyanothece 51142, a unicellular diazotrophic cyanobacterium important in the marine nitrogen cycle. Proc Natl Acad Sci U S A105:15094–15099
    [Google Scholar]
  22. Westfall H. N., Charon N. W., Peterson D. E.. 1983; Multiple pathways for isoleucine biosynthesis in the spirochete Leptospira. J Bacteriol154:846–853
    [Google Scholar]
  23. Xu H., Zhang Y. Z., Guo X. K., Ren S., Staempfli A. A., Chiao J., Jiang W., Zhao G.. 2004; Isoleucine biosynthesis in Leptospira interrogans serotype lai strain 56601 proceeds via a threonine-independent pathway. J Bacteriol186:5400–5409
    [Google Scholar]
http://instance.metastore.ingenta.com/content/journal/micro/10.1099/mic.0.031799-0
Loading
/content/journal/micro/10.1099/mic.0.031799-0
Loading

Data & Media loading...

Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error