The t-SNARE AtVAM3p Resides on the Prevacuolar Compartment in Arabidopsis Root Cells

Sanderfoot, Anton A.; Kovaleva, Valentina; Zheng, Haiyan; Raikhel, Natasha V.

doi:10.1104/pp.121.3.929

Cited by 73 publications

(73 citation statements)

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“…Because each of these gene families contains three paralogous members that show high protein sequence identity, it was possible that the individual members of each family would perform redundant functions. However, prior studies have suggested that this was not the case, because individual members within each group were found to have distinct localizations (Sato et al, 1997;Sanderfoot et al, 1999;Bassham et al, 2000). Consistent with these results, we have found that gene disruptions in single syntaxin genes from these families are lethal to the male gametophyte, indicating that each member of these gene families has a unique essential function.…”

Section: Discussionsupporting

confidence: 80%

“…This suggests that the complementation is not due to overexpression of the transgene; in fact, it appears that the amount of T7-SYP21 protein is much less than the endogenous SYP21 protein. The amount of T7-SYP21 being produced is also less than the amount of SYP22 in these plants (see Sanderfoot et al, 1999). This is Leaf tissue was homogenized, and equivalent amounts of total protein from wild-type (lane 1), SYP21/syp21-1 plants (lane 2), and syp21-1::T7-SYP21 plants (lane 3) were separated by SDS-PAGE and blotted with SYP21 antiserum.…”

Section: Discussionmentioning

confidence: 99%

“…Plants constitutively expressing a transgene encoding an epitope-tagged version of SYP21 (T7-SYP21) have been described (Sanderfoot et al, 1999), and pollen from these homozygous plants was used to fertilize SYP21/syp21-1 heterozygotes, resulting in several F1 progeny that carried a T7-SYP21 transgene and the syp21-1 insertion, both in a heterozygous state. Several representative plants were allowed to self, and their progeny were examined.…”

Section: Complementation Of the Syp21-1-associated Lethalitymentioning

confidence: 99%

“…We have subdivided these syntaxins into eight groups that contain 10 gene families of one to five paralogous members . Our initial focus has been on the genes of the SYP2 and SYP4 families.The SYP2 family is represented by three genes ( SYP21 , SYP22 , and SYP23 ) that encode syntaxins that reside on the prevacuolar compartment of Arabidopsis cells (Sanderfoot et al, 1999), although SYP22 also has been reported to localize to the vacuole in some cell types (Sato et al, 1997). The members of the SYP2 family are most similar to the yeast prevacuolar syntaxin Pep12p (Becherer et al, 1996) and to mammalian syntaxins 7 and 13 (which reside on various endosomal compartments; Prekeris et al, 1999).…”

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Disruption of Individual Members of Arabidopsis Syntaxin Gene Families Indicates Each Has Essential Functions

et al. 2001

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Syntaxins are a large group of proteins found in all eukaryotes involved in the fusion of transport vesicles to target membranes. Twenty-four syntaxins grouped into 10 gene families are found in the model plant Arabidopsis thaliana , each group containing one to five paralogous members. The Arabidopsis SYP2 and SYP4 gene families contain three members each that share 60 to 80% protein sequence identity. Gene disruptions of the yeast ( Saccharomyces cerevisiae ) orthologs of the SYP2 and SYP4 gene families (Pep12p and Tlg2p, respectively) indicate that these syntaxins are not essential for growth in yeast. However, we have isolated and characterized gene disruptions in two genes from each family, finding that disruption of individual syntaxins from these families is lethal in the male gametophyte of Arabidopsis. Complementation of the syp21-1 gene disruption with its cognate transgene indicated that the lethality is linked to the loss of the single syntaxin gene. Thus, it is clear that each syntaxin in the SYP2 and SYP4 families serves an essential nonredundant function. INTRODUCTIONThe syntaxins are a large evolutionarily conserved family of proteins required for fusion of transport vesicles in eukaryotic cells. Individual syntaxins reside on the organelles of the endomembrane system in which it is believed that they assemble with other proteins of the SNARE (for soluble N -ethylmaleimide sensitive factor attachment protein receptor) family to form t-SNARE complexes. The t-SNARE complex serves as a binding site for v-SNAREs on the transport vesicle, and association of the v-SNARE with the t-SNARE complex is thought to drive membrane fusion (McNew et al., 2000).The Saccharomyces cerevisiae genome encodes eight syntaxins (Pelham, 1999), two of which, Sso1p and Sso2p, are functionally redundant (Aalto et al., 1993). Gene disruptions of all yeast syntaxins have been characterized, with only the ER syntaxin Ufe1p, the Golgi syntaxin Sed5p, and one of either Sso1p or Sso2p (plasma membrane syntaxins) being essential for viability, although mutations of the other syntaxins result in large defects in vesicle trafficking (reviewed in Pelham, 1999). The effect of the loss of a syntaxin gene in a multicellular eukaryote has been examined in only a few cases. The Caenorhabditis elegans unc-64 mutant, which corresponds to a plasma membrane syntaxin, has pleiotrophic defects in coordination and neurotransmitter release (Ogawa et al., 1998). Mutants in Drosophila melanogaster syntaxin 1 can be examined in flies that are mosaics of mutant and wild-type cells; these flies show multiple defects in many organs, including a failure to complete cellularization in the eye (Schulze and Bellen, 1996;Burgess et al., 1997). In the plant Arabidopsis thaliana , mutations in the KNOLLE gene, which encodes a syntaxin (now called SYP111; see Sanderfoot et al., 2000) involved in cytokinesis, lead to defects in the embryo, eventually resulting in seedling lethality (Lukowitz et al., 1996).The genome of Arabidopsis encodes 24 syntaxins that we h...

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Section: Discussionsupporting

confidence: 80%

Section: Discussionmentioning

confidence: 99%

Section: Complementation Of the Syp21-1-associated Lethalitymentioning

confidence: 99%

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Disruption of Individual Members of Arabidopsis Syntaxin Gene Families Indicates Each Has Essential Functions

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“…The Arabidopsis protein was also initially reported to be located on the tonoplast in shoot apical meristems (Sato et al, 1997). However, further examination of the localization of AtVAM3 in different tissues by gradient fractionation and by immunoelectron microscopy using both specific antibodies and epitope tagging demonstrated that in roots and leaves, AtVAM3 is found on the PVC, where it co-localizes with AtPEP12, and is not detectable on the tonoplast (Sanderfoot et al, 1999). AtVAM3 therefore is probably involved in vesicle transport from the transGolgi network to the PVC or in the fusion of prevacuoles, rather than in the transport from the PVC to the vacuole, at least in roots and leaves.…”

Section: Are Plant Cells Just Yeast Cells With Chloroplasts?mentioning

confidence: 99%