An N-terminal diacidic motif is required for trafficking of the maize aquaporins ZmPIP2;4 and ZmPIP2;5 to the plasma membrane

E. Zelazny, U. Miecielica, J.W. Borst, M.A. Hemminga, F. Chaumont

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Abstract

Maize plasma membrane aquaporins (ZmPIPs, where PIP is the plasma membrane intrinsic protein) fall into two groups, ZmPIP1s and ZmPIP2s, which, when expressed alone in mesophyll protoplasts, are found in different subcellular locations. Whereas ZmPIP1s are retained in the endoplasmic reticulum (ER), ZmPIP2s are found in the plasma membrane (PM). We previously showed that, when co-expressed with ZmPIP2s, ZmPIP1s are relocalized to the PM, and that this relocalization results from the formation of hetero-oligomers between ZmPIP1s and ZmPIP2s. To determine the domains responsible for the ER retention and PM localization, respectively, of ZmPIP1s and ZmPIP2s, truncated and mutated ZmPIPs were generated, together with chimeric proteins created by swapping the N- or C-terminal regions of ZmPIP2s and ZmPIP1s. These mutated proteins were fused to the mYFP and/or mCFP, and the fusion proteins were expressed in maize mesophyll protoplasts, and were then localized by microscopy. This allowed us to identify a diacidic motif, DIE (Asp-Ile-Glu), at position 4¿6 of the N-terminus of ZmPIP2;5, that is essential for ER export. This motif was conserved and functional in ZmPIP2;4, but was absent in ZmPIP2;1. In addition, we showed that the N-terminus of ZmPIP2;5 was not sufficient to cause the export of ZmPIP1;2 from the ER. A study of ZmPIP1;2 mutants suggested that the N- and C-termini of this protein are probably not involved in ER retention. Together, these results show that the trafficking of maize PM aquaporins is differentially regulated depending on the isoform, and involves a specific signal and mechanism.
LanguageEnglish
Pages346-355
JournalThe Plant Journal
Volume57
Issue number2
DOIs
Publication statusPublished - 2009

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Aquaporin 4
aquaporins
Zea mays
Endoplasmic Reticulum
plasma membrane
endoplasmic reticulum
Cell Membrane
corn
Aquaporins
Protoplasts
mesophyll
plant-incorporated protectants
protoplasts
recombinant fusion proteins
Proteins
proteins
Protein C
membrane proteins
blood proteins
Blood Proteins

Keywords

  • water channel
  • endoplasmic-reticulum
  • subcellular-localization
  • polarized trafficking
  • arginine methylation
  • surface expression
  • acidic sequence
  • quality-control
  • plant-cells
  • protein

Cite this

Zelazny, E. ; Miecielica, U. ; Borst, J.W. ; Hemminga, M.A. ; Chaumont, F. / An N-terminal diacidic motif is required for trafficking of the maize aquaporins ZmPIP2;4 and ZmPIP2;5 to the plasma membrane. In: The Plant Journal. 2009 ; Vol. 57, No. 2. pp. 346-355.
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abstract = "Maize plasma membrane aquaporins (ZmPIPs, where PIP is the plasma membrane intrinsic protein) fall into two groups, ZmPIP1s and ZmPIP2s, which, when expressed alone in mesophyll protoplasts, are found in different subcellular locations. Whereas ZmPIP1s are retained in the endoplasmic reticulum (ER), ZmPIP2s are found in the plasma membrane (PM). We previously showed that, when co-expressed with ZmPIP2s, ZmPIP1s are relocalized to the PM, and that this relocalization results from the formation of hetero-oligomers between ZmPIP1s and ZmPIP2s. To determine the domains responsible for the ER retention and PM localization, respectively, of ZmPIP1s and ZmPIP2s, truncated and mutated ZmPIPs were generated, together with chimeric proteins created by swapping the N- or C-terminal regions of ZmPIP2s and ZmPIP1s. These mutated proteins were fused to the mYFP and/or mCFP, and the fusion proteins were expressed in maize mesophyll protoplasts, and were then localized by microscopy. This allowed us to identify a diacidic motif, DIE (Asp-Ile-Glu), at position 4¿6 of the N-terminus of ZmPIP2;5, that is essential for ER export. This motif was conserved and functional in ZmPIP2;4, but was absent in ZmPIP2;1. In addition, we showed that the N-terminus of ZmPIP2;5 was not sufficient to cause the export of ZmPIP1;2 from the ER. A study of ZmPIP1;2 mutants suggested that the N- and C-termini of this protein are probably not involved in ER retention. Together, these results show that the trafficking of maize PM aquaporins is differentially regulated depending on the isoform, and involves a specific signal and mechanism.",
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An N-terminal diacidic motif is required for trafficking of the maize aquaporins ZmPIP2;4 and ZmPIP2;5 to the plasma membrane. / Zelazny, E.; Miecielica, U.; Borst, J.W.; Hemminga, M.A.; Chaumont, F.

In: The Plant Journal, Vol. 57, No. 2, 2009, p. 346-355.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - An N-terminal diacidic motif is required for trafficking of the maize aquaporins ZmPIP2;4 and ZmPIP2;5 to the plasma membrane

AU - Zelazny, E.

AU - Miecielica, U.

AU - Borst, J.W.

AU - Hemminga, M.A.

AU - Chaumont, F.

N1 - Online first

PY - 2009

Y1 - 2009

N2 - Maize plasma membrane aquaporins (ZmPIPs, where PIP is the plasma membrane intrinsic protein) fall into two groups, ZmPIP1s and ZmPIP2s, which, when expressed alone in mesophyll protoplasts, are found in different subcellular locations. Whereas ZmPIP1s are retained in the endoplasmic reticulum (ER), ZmPIP2s are found in the plasma membrane (PM). We previously showed that, when co-expressed with ZmPIP2s, ZmPIP1s are relocalized to the PM, and that this relocalization results from the formation of hetero-oligomers between ZmPIP1s and ZmPIP2s. To determine the domains responsible for the ER retention and PM localization, respectively, of ZmPIP1s and ZmPIP2s, truncated and mutated ZmPIPs were generated, together with chimeric proteins created by swapping the N- or C-terminal regions of ZmPIP2s and ZmPIP1s. These mutated proteins were fused to the mYFP and/or mCFP, and the fusion proteins were expressed in maize mesophyll protoplasts, and were then localized by microscopy. This allowed us to identify a diacidic motif, DIE (Asp-Ile-Glu), at position 4¿6 of the N-terminus of ZmPIP2;5, that is essential for ER export. This motif was conserved and functional in ZmPIP2;4, but was absent in ZmPIP2;1. In addition, we showed that the N-terminus of ZmPIP2;5 was not sufficient to cause the export of ZmPIP1;2 from the ER. A study of ZmPIP1;2 mutants suggested that the N- and C-termini of this protein are probably not involved in ER retention. Together, these results show that the trafficking of maize PM aquaporins is differentially regulated depending on the isoform, and involves a specific signal and mechanism.

AB - Maize plasma membrane aquaporins (ZmPIPs, where PIP is the plasma membrane intrinsic protein) fall into two groups, ZmPIP1s and ZmPIP2s, which, when expressed alone in mesophyll protoplasts, are found in different subcellular locations. Whereas ZmPIP1s are retained in the endoplasmic reticulum (ER), ZmPIP2s are found in the plasma membrane (PM). We previously showed that, when co-expressed with ZmPIP2s, ZmPIP1s are relocalized to the PM, and that this relocalization results from the formation of hetero-oligomers between ZmPIP1s and ZmPIP2s. To determine the domains responsible for the ER retention and PM localization, respectively, of ZmPIP1s and ZmPIP2s, truncated and mutated ZmPIPs were generated, together with chimeric proteins created by swapping the N- or C-terminal regions of ZmPIP2s and ZmPIP1s. These mutated proteins were fused to the mYFP and/or mCFP, and the fusion proteins were expressed in maize mesophyll protoplasts, and were then localized by microscopy. This allowed us to identify a diacidic motif, DIE (Asp-Ile-Glu), at position 4¿6 of the N-terminus of ZmPIP2;5, that is essential for ER export. This motif was conserved and functional in ZmPIP2;4, but was absent in ZmPIP2;1. In addition, we showed that the N-terminus of ZmPIP2;5 was not sufficient to cause the export of ZmPIP1;2 from the ER. A study of ZmPIP1;2 mutants suggested that the N- and C-termini of this protein are probably not involved in ER retention. Together, these results show that the trafficking of maize PM aquaporins is differentially regulated depending on the isoform, and involves a specific signal and mechanism.

KW - water channel

KW - endoplasmic-reticulum

KW - subcellular-localization

KW - polarized trafficking

KW - arginine methylation

KW - surface expression

KW - acidic sequence

KW - quality-control

KW - plant-cells

KW - protein

U2 - 10.1111/j.1365-313X.2008.03691.x

DO - 10.1111/j.1365-313X.2008.03691.x

M3 - Article

VL - 57

SP - 346

EP - 355

JO - The Plant Journal

T2 - The Plant Journal

JF - The Plant Journal

SN - 0960-7412

IS - 2

ER -