Elevation of free proline and proline-rich protein levels by simultaneous manipulations of proline biosynthesis and degradation in plants

Hanan Stein, Arik Honig, Gad Miller, Oran Erster, Haviva Eilenberg, Laszlo N. Csonka, László Szabados, Csaba Koncz, Aviah Zilberstein

Research output: Contribution to journalArticlepeer-review

55 Scopus citations


Proline-rich proteins (PRP) are cell wall and plasma membrane-anchored factors involved in cell wall maintenance and its stress-induced fortification. Here we compare the synthesis of P5C as the proline (Pro) precursor in the cytosol and chloroplast by an introduced alien system and evaluate correlation between PRP synthesis and free Pro accumulation in plants. We developed a Pro over-producing system by generating transgenic tobacco plants overexpressing E. coli P5C biosynthetic enzymes; Pro-indifferent gamma-glutamyl kinase 74 (GK74) and gamma-glutamylphosphate reductase (GPR), as well as antisensing proline dehydrogenase (ProDH) transcription. GK74 and GPR enzymes were targeted either to the cytosol or plastids. Molecular analyses indicated that the two bacterial enzymes are efficiently expressed in plant cells, correctly targeted to the cytosol or chloroplasts, and processed to active enzymatic complexes in the two compartments. Maximal Pro increase is obtained when GK74 and GPR are active in chloroplasts, and ProDH mRNA level is reduced by anti-sense silencing, resulting in more than 50-fold higher Pro content compared to that of wild type tobacco plants. The Pro over-producing system efficiently works in tobacco and Arabidopsis. The elevation of Pro levels promotes accumulation of ectopically expressed Cell Wall Linker Protein (AtCWLP), a membrane protein with an external Pro-rich domain. These results suggest that the Pro-generating system can support endogenous or alien PRP production in plants.

Original languageEnglish
Pages (from-to)140-150
Number of pages11
JournalPlant Science
Issue number2
StatePublished - Aug 2011

Bibliographical note

Funding Information:
The constructive discussions with Dr. E. Sadot (The Volcani Institute, Bet Dagan, Israel) and Prof. P. Goloubinoff (Université de Lausanne, Lausanne, Switzerland) are highly appreciated. This work was supported by the European Union FP5 grant ( OLRT-2001-00841 ) (C.K., L.S and A.Z.) and NIH R01-GM3199994 (LNC). C.K., L.S. and A.Z. are members of the EU COST action FA0605 INPAS that inspired this issue.


  • CWLP
  • ProA
  • ProB74
  • Proline
  • Proline-rich proteins
  • Salt stress


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