Limits...
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.

Show MeSH

Related in: MedlinePlus

Cell elongation and root hair growth in keule mutants. (A–D) Mutant seedlings were germinated in the light (left) or dark (right). keule (B), keule-like (C), and knolle (D) mutants are capable of elongation, but not to the same extent as wild-type (A). (E) KEULE is only weakly expressed in etiolated hypocotyls. Anticofillin antibody was used as a load control. (F–K) Root hairs are absent (K) or stunted and radially swollen (H) in keule mutants, but of normal length in other cytokinesis-defective mutants. Root hairs are stained with methylene blue. Each keule allele exhibits a range of phenotypes, though the range may differ in a given allele. In contrast to keule mutants, keule-like (I) and knolle (J) mutants grow long root hairs. (F and K) Clearing preparation of wild-type (F) and keule (K) seedling. Note that the basal portion of keule seedlings have root-like characteristics. Arrows point to root hairs. h, hypocotyl; r, root; t, root tip. KEULE alleles: MM125 in B and H; G67 in K. Bars: (F) 270 μm; (K) 200 μm.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2195996&req=5

Figure 8: Cell elongation and root hair growth in keule mutants. (A–D) Mutant seedlings were germinated in the light (left) or dark (right). keule (B), keule-like (C), and knolle (D) mutants are capable of elongation, but not to the same extent as wild-type (A). (E) KEULE is only weakly expressed in etiolated hypocotyls. Anticofillin antibody was used as a load control. (F–K) Root hairs are absent (K) or stunted and radially swollen (H) in keule mutants, but of normal length in other cytokinesis-defective mutants. Root hairs are stained with methylene blue. Each keule allele exhibits a range of phenotypes, though the range may differ in a given allele. In contrast to keule mutants, keule-like (I) and knolle (J) mutants grow long root hairs. (F and K) Clearing preparation of wild-type (F) and keule (K) seedling. Note that the basal portion of keule seedlings have root-like characteristics. Arrows point to root hairs. h, hypocotyl; r, root; t, root tip. KEULE alleles: MM125 in B and H; G67 in K. Bars: (F) 270 μm; (K) 200 μm.

Mentions: Given KEULE's gene identity, we considered the possibility that, in addition to its role in cytokinesis, KEULE might regulate other vesicle trafficking events in the plant cell. We investigated two processes that, like cytokinesis, require an extensive remobilization of resources mediated via membrane trafficking: cell elongation and root hair growth. A striking example of rapid cell elongation in plants occurs in etiolated seedlings: hypocotyls of seedlings germinated in the dark are roughly fivefold longer than light-germinated controls (Fig. 8 A). To test whether keule and other cytokinesis-defective mutants were capable of elongation, we germinated these in the dark. keule and keule-like mutants are capable of elongation (Fig. 8B and Fig. C), although not to the same extent as the wild-type (Fig. 8 A; compare up to roughly threefold elongation in the mutants with roughly fivefold elongation in the wild-type). Hypocotyl length is determined largely by cell expansion, but also by cell division, and the effect of keule and keule-like mutants on the extent of elongation is likely to be a (direct or indirect) consequence of the cytokinesis defect. In the case of knolle seedlings, which also appear capable of elongation (Fig. 8 C), this experiment is complicated by the severe germination defect of knolle mutants. We also tested whether KEULE is enriched in rapidly elongating cells as it is in dividing cells. We detected only low levels of KEULE expression in etiolated hypocotyls (Fig. 8 E). Similarly, KEULE is weakly expressed in the stems (mostly quiescent or elongating tissue, Fig. 5 B) and is present at higher levels in the dividing (root tip) than in the elongating moiety (root length) of the root (Fig. 5 B; see Materials and Methods for sample preparation). We conclude that KEULE is not absolutely required for cell elongation.


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)

Cell elongation and root hair growth in keule mutants. (A–D) Mutant seedlings were germinated in the light (left) or dark (right). keule (B), keule-like (C), and knolle (D) mutants are capable of elongation, but not to the same extent as wild-type (A). (E) KEULE is only weakly expressed in etiolated hypocotyls. Anticofillin antibody was used as a load control. (F–K) Root hairs are absent (K) or stunted and radially swollen (H) in keule mutants, but of normal length in other cytokinesis-defective mutants. Root hairs are stained with methylene blue. Each keule allele exhibits a range of phenotypes, though the range may differ in a given allele. In contrast to keule mutants, keule-like (I) and knolle (J) mutants grow long root hairs. (F and K) Clearing preparation of wild-type (F) and keule (K) seedling. Note that the basal portion of keule seedlings have root-like characteristics. Arrows point to root hairs. h, hypocotyl; r, root; t, root tip. KEULE alleles: MM125 in B and H; G67 in K. Bars: (F) 270 μm; (K) 200 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2195996&req=5

Figure 8: Cell elongation and root hair growth in keule mutants. (A–D) Mutant seedlings were germinated in the light (left) or dark (right). keule (B), keule-like (C), and knolle (D) mutants are capable of elongation, but not to the same extent as wild-type (A). (E) KEULE is only weakly expressed in etiolated hypocotyls. Anticofillin antibody was used as a load control. (F–K) Root hairs are absent (K) or stunted and radially swollen (H) in keule mutants, but of normal length in other cytokinesis-defective mutants. Root hairs are stained with methylene blue. Each keule allele exhibits a range of phenotypes, though the range may differ in a given allele. In contrast to keule mutants, keule-like (I) and knolle (J) mutants grow long root hairs. (F and K) Clearing preparation of wild-type (F) and keule (K) seedling. Note that the basal portion of keule seedlings have root-like characteristics. Arrows point to root hairs. h, hypocotyl; r, root; t, root tip. KEULE alleles: MM125 in B and H; G67 in K. Bars: (F) 270 μm; (K) 200 μm.
Mentions: Given KEULE's gene identity, we considered the possibility that, in addition to its role in cytokinesis, KEULE might regulate other vesicle trafficking events in the plant cell. We investigated two processes that, like cytokinesis, require an extensive remobilization of resources mediated via membrane trafficking: cell elongation and root hair growth. A striking example of rapid cell elongation in plants occurs in etiolated seedlings: hypocotyls of seedlings germinated in the dark are roughly fivefold longer than light-germinated controls (Fig. 8 A). To test whether keule and other cytokinesis-defective mutants were capable of elongation, we germinated these in the dark. keule and keule-like mutants are capable of elongation (Fig. 8B and Fig. C), although not to the same extent as the wild-type (Fig. 8 A; compare up to roughly threefold elongation in the mutants with roughly fivefold elongation in the wild-type). Hypocotyl length is determined largely by cell expansion, but also by cell division, and the effect of keule and keule-like mutants on the extent of elongation is likely to be a (direct or indirect) consequence of the cytokinesis defect. In the case of knolle seedlings, which also appear capable of elongation (Fig. 8 C), this experiment is complicated by the severe germination defect of knolle mutants. We also tested whether KEULE is enriched in rapidly elongating cells as it is in dividing cells. We detected only low levels of KEULE expression in etiolated hypocotyls (Fig. 8 E). Similarly, KEULE is weakly expressed in the stems (mostly quiescent or elongating tissue, Fig. 5 B) and is present at higher levels in the dividing (root tip) than in the elongating moiety (root length) of the root (Fig. 5 B; see Materials and Methods for sample preparation). We conclude that KEULE is not absolutely required for cell elongation.

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