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The cytokinesis gene KEULE encodes a Sec1 protein that binds the syntaxin KNOLLE.

Assaad FF, Huet Y, Mayer U, Jürgens G - J. Cell Biol. (2001)

Bottom Line: KEULE is characteristic of a Sec1 protein in that it appears to exist in two forms: soluble or peripherally associated with membranes.More importantly, KEULE binds the cytokinesis-specific syntaxin KNOLLE.Sec1 proteins are key regulators of vesicle trafficking, capable of integrating a large number of intra- and/or intercellular signals.

View Article: PubMed Central - PubMed

Affiliation: Genetics and Microbiology Institute, Ludwig Maximilians University, D-80638 Munich, Germany. fassaad@andrew2.stanford.edu

ABSTRACT
KEULE is required for cytokinesis in Arabidopsis thaliana. We have positionally cloned the KEULE gene and shown that it encodes a Sec1 protein. KEULE is expressed throughout the plant, yet appears enriched in dividing tissues. Cytokinesis-defective mutant sectors were observed in all somatic tissues upon transformation of wild-type plants with a KEULE-green fluorescent protein gene fusion, suggesting that KEULE is required not only during embryogenesis, but at all stages of the plant's life cycle. KEULE is characteristic of a Sec1 protein in that it appears to exist in two forms: soluble or peripherally associated with membranes. More importantly, KEULE binds the cytokinesis-specific syntaxin KNOLLE. Sec1 proteins are key regulators of vesicle trafficking, capable of integrating a large number of intra- and/or intercellular signals. As a cytokinesis-related Sec1 protein, KEULE appears to represent a novel link between cell cycle progression and the membrane fusion apparatus.

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Sequence alignment of the KEULE protein. KEULE has two closely related homologues in Arabidopsis, AtSec1a and AtSec1b. These three proteins are clearly much closer to each other than to their homologues in other organisms. The Sec1 signature was defined before the publication of plant Sec1s as consisting of 23 highly conserved residues, boxed in this figure. Note that KEULE contains 21 of these 23 residues. The two residues that do not fit in this signature are identical in all three Arabidopsis Sec1s and in one instance, they are replaced by a conserved amino acid (I in lieu of L, KEULE amino acid 269). Rop, Drosophila nSec1 homologue; Sly1, yeast Sec1 homologue involved in ER-Golgi transport; accession numbers are to be found in Halachmi and Lev 1996. Plant Sec1 homologue sequence data are available from GenBank/EMBL/DDBJ under accession nos.: KEULE, AF331066; AtSec1a, AF335539; AtSec1b, CAB40953. Note that we do not show the entire proteins but only the domains with higher degrees of conservation. Black boxes highlight identical residues and gray boxes shade conserved residues.
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Figure 3: Sequence alignment of the KEULE protein. KEULE has two closely related homologues in Arabidopsis, AtSec1a and AtSec1b. These three proteins are clearly much closer to each other than to their homologues in other organisms. The Sec1 signature was defined before the publication of plant Sec1s as consisting of 23 highly conserved residues, boxed in this figure. Note that KEULE contains 21 of these 23 residues. The two residues that do not fit in this signature are identical in all three Arabidopsis Sec1s and in one instance, they are replaced by a conserved amino acid (I in lieu of L, KEULE amino acid 269). Rop, Drosophila nSec1 homologue; Sly1, yeast Sec1 homologue involved in ER-Golgi transport; accession numbers are to be found in Halachmi and Lev 1996. Plant Sec1 homologue sequence data are available from GenBank/EMBL/DDBJ under accession nos.: KEULE, AF331066; AtSec1a, AF335539; AtSec1b, CAB40953. Note that we do not show the entire proteins but only the domains with higher degrees of conservation. Black boxes highlight identical residues and gray boxes shade conserved residues.

Mentions: The KEULE gene is 28–30% identical (49–50% similar) to worm (unc18), fly (Rop), and mammalian (munc18/n-Sec1) Sec1 homologues (Rop shown in Fig. 3). The homology is spread over the entire coding region. The Sec1 “signature,” as defined by Halachmi and Lev 1996, consists of 23 highly conserved residues (boxed in Fig. 3). KEULE contains 21 of these 23 residues (Fig. 3). One of the nonidentical residues has been replaced by a conserved residue. The KEULE protein appears hydrophilic, as expected for a Sec1. The nature of the fast-neutron– and x-ray–induced mutations described above and the observation that all 19 alleles of keule have very comparable phenotypes are a strong indication that we have identified alleles of keule.


The cytokinesis gene KEULE encodes a Sec1 protein that binds the syntaxin KNOLLE.

Assaad FF, Huet Y, Mayer U, Jürgens G - J. Cell Biol. (2001)

Sequence alignment of the KEULE protein. KEULE has two closely related homologues in Arabidopsis, AtSec1a and AtSec1b. These three proteins are clearly much closer to each other than to their homologues in other organisms. The Sec1 signature was defined before the publication of plant Sec1s as consisting of 23 highly conserved residues, boxed in this figure. Note that KEULE contains 21 of these 23 residues. The two residues that do not fit in this signature are identical in all three Arabidopsis Sec1s and in one instance, they are replaced by a conserved amino acid (I in lieu of L, KEULE amino acid 269). Rop, Drosophila nSec1 homologue; Sly1, yeast Sec1 homologue involved in ER-Golgi transport; accession numbers are to be found in Halachmi and Lev 1996. Plant Sec1 homologue sequence data are available from GenBank/EMBL/DDBJ under accession nos.: KEULE, AF331066; AtSec1a, AF335539; AtSec1b, CAB40953. Note that we do not show the entire proteins but only the domains with higher degrees of conservation. Black boxes highlight identical residues and gray boxes shade conserved residues.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2195996&req=5

Figure 3: Sequence alignment of the KEULE protein. KEULE has two closely related homologues in Arabidopsis, AtSec1a and AtSec1b. These three proteins are clearly much closer to each other than to their homologues in other organisms. The Sec1 signature was defined before the publication of plant Sec1s as consisting of 23 highly conserved residues, boxed in this figure. Note that KEULE contains 21 of these 23 residues. The two residues that do not fit in this signature are identical in all three Arabidopsis Sec1s and in one instance, they are replaced by a conserved amino acid (I in lieu of L, KEULE amino acid 269). Rop, Drosophila nSec1 homologue; Sly1, yeast Sec1 homologue involved in ER-Golgi transport; accession numbers are to be found in Halachmi and Lev 1996. Plant Sec1 homologue sequence data are available from GenBank/EMBL/DDBJ under accession nos.: KEULE, AF331066; AtSec1a, AF335539; AtSec1b, CAB40953. Note that we do not show the entire proteins but only the domains with higher degrees of conservation. Black boxes highlight identical residues and gray boxes shade conserved residues.
Mentions: The KEULE gene is 28–30% identical (49–50% similar) to worm (unc18), fly (Rop), and mammalian (munc18/n-Sec1) Sec1 homologues (Rop shown in Fig. 3). The homology is spread over the entire coding region. The Sec1 “signature,” as defined by Halachmi and Lev 1996, consists of 23 highly conserved residues (boxed in Fig. 3). KEULE contains 21 of these 23 residues (Fig. 3). One of the nonidentical residues has been replaced by a conserved residue. The KEULE protein appears hydrophilic, as expected for a Sec1. The nature of the fast-neutron– and x-ray–induced mutations described above and the observation that all 19 alleles of keule have very comparable phenotypes are a strong indication that we have identified alleles of keule.

Bottom Line: KEULE is characteristic of a Sec1 protein in that it appears to exist in two forms: soluble or peripherally associated with membranes.More importantly, KEULE binds the cytokinesis-specific syntaxin KNOLLE.Sec1 proteins are key regulators of vesicle trafficking, capable of integrating a large number of intra- and/or intercellular signals.

View Article: PubMed Central - PubMed

Affiliation: Genetics and Microbiology Institute, Ludwig Maximilians University, D-80638 Munich, Germany. fassaad@andrew2.stanford.edu

ABSTRACT
KEULE is required for cytokinesis in Arabidopsis thaliana. We have positionally cloned the KEULE gene and shown that it encodes a Sec1 protein. KEULE is expressed throughout the plant, yet appears enriched in dividing tissues. Cytokinesis-defective mutant sectors were observed in all somatic tissues upon transformation of wild-type plants with a KEULE-green fluorescent protein gene fusion, suggesting that KEULE is required not only during embryogenesis, but at all stages of the plant's life cycle. KEULE is characteristic of a Sec1 protein in that it appears to exist in two forms: soluble or peripherally associated with membranes. More importantly, KEULE binds the cytokinesis-specific syntaxin KNOLLE. Sec1 proteins are key regulators of vesicle trafficking, capable of integrating a large number of intra- and/or intercellular signals. As a cytokinesis-related Sec1 protein, KEULE appears to represent a novel link between cell cycle progression and the membrane fusion apparatus.

Show MeSH
Related in: MedlinePlus