TY - JOUR
T1 - Translational regulation of Arabidopsis XIPOTL1 is modulated by phosphocholine levels via the phylogenetically conserved upstream open reading frame 30
AU - Alatorre-Cobos, Fulgencio
AU - Cruz-Ramírez, Alfredo
AU - Hayden, Celine A.
AU - Pérez-Torres, Claudia Anahí
AU - Chauvin, Anne Laure
AU - Ibarra-Laclette, Enrique
AU - Alva-Cortés, Erika
AU - Jorgensen, Richard A.
AU - Herrera-Estrella, Luis
N1 - Funding Information:
This work was supported in part by the Howard Medical Institute (grant 55003677) to LH-E.
PY - 2012/9
Y1 - 2012/9
N2 - In Arabidopsis thaliana, XIPOTL1 encodes a phosphoethanolamine N-methyltransferase with a central role in phosphatidylcholine biosynthesis via the methylation pathway. To gain further insights into the mechanisms that regulate XIPOTL1 expression, the effect of upstream open reading frame 30 (uORF30) on the translation of the major ORF (mORF) in the presence or absence of endogenous choline (Cho) or phosphocholine (PCho) was analysed in Arabidopsis seedlings. Doseresponse assays with Cho or PCho revealed that both metabolites at physiological concentrations are able to induce the translational repression of a mORF located downstream of the intact uORF30, without significantly altering its mRNA levels. PCho profiles showed a correlation between increased endogenous PCho levels and translation efficiency of a uORF30-containing mORF, while no correlation was detectable with Cho levels. Enhanced expression of a uORF30-containing mORF and decreased PCho levels were observed in the xipotl1 mutant background relative to wild type, suggesting that PCho is the true mediator of uORF30-driven translational repression. In Arabidopsis, endogenous PCho content increases during plant development and affects root meristem size, cell division, and cell elongation. Because XIPOTL1 is preferentially expressed in Arabidopsis root tips, higher PCho levels are found in roots than shoots, and there is a higher sensitivity of this tissue to translational uORF30-mediated control, it is proposed that root tips are the main site for PCho biosynthesis in Arabidopsis.
AB - In Arabidopsis thaliana, XIPOTL1 encodes a phosphoethanolamine N-methyltransferase with a central role in phosphatidylcholine biosynthesis via the methylation pathway. To gain further insights into the mechanisms that regulate XIPOTL1 expression, the effect of upstream open reading frame 30 (uORF30) on the translation of the major ORF (mORF) in the presence or absence of endogenous choline (Cho) or phosphocholine (PCho) was analysed in Arabidopsis seedlings. Doseresponse assays with Cho or PCho revealed that both metabolites at physiological concentrations are able to induce the translational repression of a mORF located downstream of the intact uORF30, without significantly altering its mRNA levels. PCho profiles showed a correlation between increased endogenous PCho levels and translation efficiency of a uORF30-containing mORF, while no correlation was detectable with Cho levels. Enhanced expression of a uORF30-containing mORF and decreased PCho levels were observed in the xipotl1 mutant background relative to wild type, suggesting that PCho is the true mediator of uORF30-driven translational repression. In Arabidopsis, endogenous PCho content increases during plant development and affects root meristem size, cell division, and cell elongation. Because XIPOTL1 is preferentially expressed in Arabidopsis root tips, higher PCho levels are found in roots than shoots, and there is a higher sensitivity of this tissue to translational uORF30-mediated control, it is proposed that root tips are the main site for PCho biosynthesis in Arabidopsis.
KW - Arabidopsis
KW - XIPOTL1
KW - mORF
KW - phosphatidylcholine
KW - phosphocholine
KW - root development
KW - translational control
KW - uORF30
UR - http://www.scopus.com/inward/record.url?scp=84865757184&partnerID=8YFLogxK
U2 - 10.1093/jxb/ers180
DO - 10.1093/jxb/ers180
M3 - Article
C2 - 22791820
AN - SCOPUS:84865757184
VL - 63
SP - 5203
EP - 5221
JO - Journal of Experimental Botany
JF - Journal of Experimental Botany
SN - 0022-0957
IS - 14
ER -