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Plasma membrane-association of SAUL1-type plant U-box armadillo repeat proteins is conserved in land plants.

Vogelmann K, Subert C, Danzberger N, Drechsel G, Bergler J, Kotur T, Burmester T, Hoth S - Front Plant Sci (2014)

Bottom Line: Phylogenetic analysis identified orthologs of SAUL1 in these plant species.Analyses of transgenic Arabidopsis plants overexpressing N-terminally masked or truncated proteins revealed that interfering with the function of SAUL1-type proteins resulted in severe growth defects.Our results suggest an ancient origin of ubiquitination at the plasma membrane in the evolution of land plants.

View Article: PubMed Central - PubMed

Affiliation: Molekulare Pflanzenphysiologie, Biozentrum Klein Flottbek, Universität Hamburg Hamburg, Germany.

ABSTRACT
Post-translational protein modification plays a pivotal role in the regulation and specific turnover of proteins. One of these important modifications is the ubiquitination of target proteins, which can occur at distinct cellular compartments. At the plasma membrane, ubiquitination regulates the internalization and thus trafficking of membrane proteins such as receptors and channels. The Arabidopsis plant U-box (PUB) armadillo repeat (PUB-ARM) ubiquitin ligase SAUL1 (SENESCENCE-ASSOCIATED UBIQUITIN LIGASE1) is part of the ubiquitination machinery at the plasma membrane. In contrast to most other PUB-ARM proteins, SAUL1 carries additional C-terminal ARM repeats responsible for plasma membrane-association. Here, we demonstrated that the C-terminal ARM repeat domain is also essential and sufficient to mediate plasma membrane-association of the closest Arabidopis paralog AtPUB43. We investigated targeting of PUB-ARM ubiquitin ligases of different plant species to find out whether plasma membrane-association of SAUL1-type PUB-ARM proteins is conserved. Phylogenetic analysis identified orthologs of SAUL1 in these plant species. Intracellular localization of transiently expressed GFP fusion proteins revealed that indeed plasma membrane-association due to additional C-terminal ARM repeats represents a conserved feature of SAUL1-type proteins. Analyses of transgenic Arabidopsis plants overexpressing N-terminally masked or truncated proteins revealed that interfering with the function of SAUL1-type proteins resulted in severe growth defects. Our results suggest an ancient origin of ubiquitination at the plasma membrane in the evolution of land plants.

No MeSH data available.


Phylogenetic relationship of PUB-ARM proteins of Arabidopsis, rice, poplar and moss. (A) Simplified Bayesian phylogenetic tree depicting the relationship among class I–IV PUB-ARM proteins, as defined by Zeng et al. (2008). The bar represents 0.5 PAM distance. The tree derived from the analysis of the 2683 amino acid alignment; the full tree in Supporting Figure S2. (B) Subtree of (A) depicting the relationship among class IV proteins, which include SAUL1-type proteins. Arabidopsis SAUL1 (AtPUB44) is highlighted in gray; the numbers at the nodes are Bayesian posterior probabilities.
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Figure 3: Phylogenetic relationship of PUB-ARM proteins of Arabidopsis, rice, poplar and moss. (A) Simplified Bayesian phylogenetic tree depicting the relationship among class I–IV PUB-ARM proteins, as defined by Zeng et al. (2008). The bar represents 0.5 PAM distance. The tree derived from the analysis of the 2683 amino acid alignment; the full tree in Supporting Figure S2. (B) Subtree of (A) depicting the relationship among class IV proteins, which include SAUL1-type proteins. Arabidopsis SAUL1 (AtPUB44) is highlighted in gray; the numbers at the nodes are Bayesian posterior probabilities.

Mentions: Two multiple sequence alignments were applied for Bayesian phylogenetic analyses. The first alignment covered 2683 amino acid positions and included the full-length proteins. In the second alignment all gaps were removed, resulting in 210 positions. Both alignments gave very similar trees, which recovered the classes I–IV of PUB-ARM proteins, as defined by Zeng et al. (2008) (Figure 3A; Supporting Figures S2, S3). SAUL1 and SAUL-like paralogs of Arabidopsis and rice are members of class IV. SAUL1 (AtPUB44) and AtPUB43 are closely related and form a common branch with three PUB-ARM proteins from rice (OsPUB23–25) and two from poplar (Pt0002s00910 and Pt0005s27480) (Figure 3B). AtPUB42 is on a different branch within class IV and is related to rice OsPUB21 and 22, as well as two proteins of poplar (Pt0008s11210 and Pt0010s14630). Six proteins of the bryophyte P. patens are related to the clade of SAUL1-like proteins of the vascular plants. In addition, five proteins from P. trichocarpa and five from P. patens form a distinct clade within class IV, which is more distantly related to SAUL1. SAUL1 orthologs within the class IV proteins displayed sequences identities of more than 40%. Comparison of SAUL1 with class I–III PUB-ARM proteins revealed low identity scores of less than 26%. In all cases and in contrast to all other PUB-ARM proteins, SAUL1-type PUB-ARM proteins consist of a clearly higher number of amino acids due to their specific domain organization, namely their elongated C-terminus that contains additional ARM repeat domains. Based on these criteria, additional BLAST searches identified putative SAUL1-type PUB-ARM proteins in all land plants listed on the phytozome website, suggesting conservation in land plants (not shown).


Plasma membrane-association of SAUL1-type plant U-box armadillo repeat proteins is conserved in land plants.

Vogelmann K, Subert C, Danzberger N, Drechsel G, Bergler J, Kotur T, Burmester T, Hoth S - Front Plant Sci (2014)

Phylogenetic relationship of PUB-ARM proteins of Arabidopsis, rice, poplar and moss. (A) Simplified Bayesian phylogenetic tree depicting the relationship among class I–IV PUB-ARM proteins, as defined by Zeng et al. (2008). The bar represents 0.5 PAM distance. The tree derived from the analysis of the 2683 amino acid alignment; the full tree in Supporting Figure S2. (B) Subtree of (A) depicting the relationship among class IV proteins, which include SAUL1-type proteins. Arabidopsis SAUL1 (AtPUB44) is highlighted in gray; the numbers at the nodes are Bayesian posterior probabilities.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3928556&req=5

Figure 3: Phylogenetic relationship of PUB-ARM proteins of Arabidopsis, rice, poplar and moss. (A) Simplified Bayesian phylogenetic tree depicting the relationship among class I–IV PUB-ARM proteins, as defined by Zeng et al. (2008). The bar represents 0.5 PAM distance. The tree derived from the analysis of the 2683 amino acid alignment; the full tree in Supporting Figure S2. (B) Subtree of (A) depicting the relationship among class IV proteins, which include SAUL1-type proteins. Arabidopsis SAUL1 (AtPUB44) is highlighted in gray; the numbers at the nodes are Bayesian posterior probabilities.
Mentions: Two multiple sequence alignments were applied for Bayesian phylogenetic analyses. The first alignment covered 2683 amino acid positions and included the full-length proteins. In the second alignment all gaps were removed, resulting in 210 positions. Both alignments gave very similar trees, which recovered the classes I–IV of PUB-ARM proteins, as defined by Zeng et al. (2008) (Figure 3A; Supporting Figures S2, S3). SAUL1 and SAUL-like paralogs of Arabidopsis and rice are members of class IV. SAUL1 (AtPUB44) and AtPUB43 are closely related and form a common branch with three PUB-ARM proteins from rice (OsPUB23–25) and two from poplar (Pt0002s00910 and Pt0005s27480) (Figure 3B). AtPUB42 is on a different branch within class IV and is related to rice OsPUB21 and 22, as well as two proteins of poplar (Pt0008s11210 and Pt0010s14630). Six proteins of the bryophyte P. patens are related to the clade of SAUL1-like proteins of the vascular plants. In addition, five proteins from P. trichocarpa and five from P. patens form a distinct clade within class IV, which is more distantly related to SAUL1. SAUL1 orthologs within the class IV proteins displayed sequences identities of more than 40%. Comparison of SAUL1 with class I–III PUB-ARM proteins revealed low identity scores of less than 26%. In all cases and in contrast to all other PUB-ARM proteins, SAUL1-type PUB-ARM proteins consist of a clearly higher number of amino acids due to their specific domain organization, namely their elongated C-terminus that contains additional ARM repeat domains. Based on these criteria, additional BLAST searches identified putative SAUL1-type PUB-ARM proteins in all land plants listed on the phytozome website, suggesting conservation in land plants (not shown).

Bottom Line: Phylogenetic analysis identified orthologs of SAUL1 in these plant species.Analyses of transgenic Arabidopsis plants overexpressing N-terminally masked or truncated proteins revealed that interfering with the function of SAUL1-type proteins resulted in severe growth defects.Our results suggest an ancient origin of ubiquitination at the plasma membrane in the evolution of land plants.

View Article: PubMed Central - PubMed

Affiliation: Molekulare Pflanzenphysiologie, Biozentrum Klein Flottbek, Universität Hamburg Hamburg, Germany.

ABSTRACT
Post-translational protein modification plays a pivotal role in the regulation and specific turnover of proteins. One of these important modifications is the ubiquitination of target proteins, which can occur at distinct cellular compartments. At the plasma membrane, ubiquitination regulates the internalization and thus trafficking of membrane proteins such as receptors and channels. The Arabidopsis plant U-box (PUB) armadillo repeat (PUB-ARM) ubiquitin ligase SAUL1 (SENESCENCE-ASSOCIATED UBIQUITIN LIGASE1) is part of the ubiquitination machinery at the plasma membrane. In contrast to most other PUB-ARM proteins, SAUL1 carries additional C-terminal ARM repeats responsible for plasma membrane-association. Here, we demonstrated that the C-terminal ARM repeat domain is also essential and sufficient to mediate plasma membrane-association of the closest Arabidopis paralog AtPUB43. We investigated targeting of PUB-ARM ubiquitin ligases of different plant species to find out whether plasma membrane-association of SAUL1-type PUB-ARM proteins is conserved. Phylogenetic analysis identified orthologs of SAUL1 in these plant species. Intracellular localization of transiently expressed GFP fusion proteins revealed that indeed plasma membrane-association due to additional C-terminal ARM repeats represents a conserved feature of SAUL1-type proteins. Analyses of transgenic Arabidopsis plants overexpressing N-terminally masked or truncated proteins revealed that interfering with the function of SAUL1-type proteins resulted in severe growth defects. Our results suggest an ancient origin of ubiquitination at the plasma membrane in the evolution of land plants.

No MeSH data available.