P-proteins in Arabidopsis are heteromeric structures involved in rapid sieve tube sealing

Jekat, Stephan B.; Ernst, Antonia M.; Bohl, Andreas von; Zielonka, Sascia; Twyman, Richard M.; Noll, Gundula A.; Prüfer, Dirk

doi:10.3389/fpls.2013.00225

Cited by 40 publications

(36 citation statements)

References 37 publications

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“…Therefore we searched for A. thaliana mRNAs that had one or more plausible miRNA complementary sites and accumulation of secondary siRNAs specifically in the I small RNA-seq samples. Six A. thaliana mRNAs that met both criteria were found: TIR1 , AFB2 , and AFB3 , which encode related and partially redundant auxin receptors 15 , BIK1 , which encodes a plasma membrane-localized kinase required for both pathogen-induced and developmental signaling 16,17 , SEOR1 , which encodes a major phloem protein that accumulates in filamentous networks in sieve tube elements and reduces photosynthate loss from the phloem upon injury 18,19 , and SCZ/HSFB4 , which encodes a predicted transcriptional repressor that is required for the formation of ground tissue stem cells in roots 20 - 22 . The induced siRNAs from these mRNAs resembled other examples of secondary siRNAs in their size distributions, double-stranded accumulation, and phasing (Figure 2A-B; Extended Data Figure 2).…”

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confidence: 99%

MicroRNAs from the parasitic plantCuscuta campestristarget host messenger RNAs

Shahid

Kim

Johnson

et al. 2017

Preprint

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First paragraphDodders (Cuscuta spp.) are obligate parasitic plants that obtain water and nutrients from the stems of host plants via specialized feeding structures called haustoria. Dodder haustoria facilitate bi-directional movement of viruses, proteins, and mRNAs between host and parasite1, but the functional effects of these movements are not clear. Here we show that C. campestris haustoria accumulate high levels of many novel microRNAs (miRNAs) while parasitizing Arabidopsis thaliana hosts. Many of these miRNAs are 22 nts long, a usually rare size of plant miRNA associated with amplification of target silencing through secondary small interfering RNA (siRNA) production2. Several A. thaliana mRNAs are targeted by C. campestris 22 nt miRNAs during parasitism, resulting in mRNA cleavage, secondary siRNA production, and decreased mRNA accumulation levels. Hosts with mutations in two of the targets supported significantly higher growth of C. campestris. Homologs of target mRNAs from diverse plants also have predicted target sites to induced C. campestris miRNAs, and the same miRNAs are expressed and active against host targets when C. campestris parasitizes a different host, Nicotiana benthamiana. These data show that C. campestris miRNAs act as trans-species regulators of host gene expression, and suggest that they may act as virulence factors during parasitism.

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confidence: 99%

MicroRNAs from the parasitic plantCuscuta campestristarget host messenger RNAs

Shahid

Kim

Johnson

et al. 2017

Preprint

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“…A fusion between the splitmRFP variants to the monomeric Emerald protein (mEmerald) was used as a control. [7][8][9][11][12][13] All BIFC constructs were introduced into Agrobacterium tumefaciens strain GV3101 pMP90 by electroporation and the resulting bacteria were infiltrated into 4-wk-old N. benthamiana plants. A. tumefaciens strain C58C1 (carrying the pCH32 helper plasmid) was co-infiltrated to inhibit gene silencing.…”

Section: Methodsmentioning

confidence: 99%

Uncertain role of MtSEO-F3 in assembly ofMedicago truncatulaforisomes

Groscurth

Müller

Visser

et al. 2014

Plant Signaling & Behavior

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Forisome structures are fine-tuned by the subunit composition Forisomes are large, spindle-shaped protein complexes that are present in the sieve elements of papilionoid legumes.1,2 In their spindle-shaped conformation, forisomes facilitate the transport of photoassimilates along the sieve tube lumen, but when the vascular system is wounded they change into a pluglike/expanded conformation that causes occlusion to prevent leakage. After tissue regeneration, forisomes can revert to their spindle-shaped conformation, thereby providing a reversible sieve tube plugging mechanism. The conformational change is calcium-dependent and can also be induced ex vivo by nonphysiological pH values.3 The forisome subunits in M. truncatula were identified by mass spectrometry following the purification of native forisomes. 4 The MtSEO-F1 protein sequence (formerly Mtfor1) was used for homology searches and transcriptional analysis, resulting in the characterization of a large sieve element occlusion (SEO) protein family spanning a wide range of dicot plants. 5,6 The group 1 SEO proteins are only present in papilionoid legumes and these represent forisome subunits, whereas members of groups 5 and 6 represent the common P-proteins in most dicot species that probably cause irreversible sieve element occlusion. [5][6][7][8] In our recent study, we expressed group 1 SEO-F genes from different legumes in a heterologous background to study their impact on forisome assembly, including the DpSEO-F1 gene from the basal papilionoid species D. panamensis. 9 The D. panamensis lineage diverged from lineages of the Old World clade, i.e., Canavalia gladiata, Lotus japonicus, and Medicago truncatula, more than 50 million years ago. The artificial protein bodies produced by expressing SEO-F genes from Lotus japonicus , , Vicia faba (VfSEO-F1), and M. truncatula ) appeared longer and thinner than wild-type forisomes, whereas the artificial forisome composed of DpSEO-F1 was similar in geometry to its native counterpart. We also found that forisome geometry was affected by coexpression, e.g., MtSEO-F2 was able to widen the forisome body Forisomes are specialized multimeric protein complexes found only in the papilionoid legumes. they undergo a reversible conformational change in response to phloem injury to enable the occlusion of sieve tubes, thus preventing the loss of photoassimilates. the individual subunits are designated by the letters SEo-F (sieve element occlusion by forisomes) and are part of the larger SEo protein family, which also includes the typical P-proteins found in most dicots and some monocots. When specific SEo-F subunits from different species are expressed in a heterologous background, they self-assemble into fully-functional artificial forisomes. however, with the exception of basal species such as Dipteryx panamensis, the geometry of these artificial forisomes differs from that of their native counterparts. Studies involving SEo-F proteins from the model legume Medicago truncatula have shown that a combination of 3 of the 4 ...

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“…32 The Fluorescent experimental studies have shown that plugging complexes in wounded transgenic plants formed distinctive plugs on most sieve plates, and these plugs ends up with characteristic gel-like transcellular strands, consistent with the known characteristics of P-proteins. 33,34 P-proteins have been identified in many dicot plants, and their structural and functional role during developmental phase and sieve plate plugging after wounding appear highly conserved even in distantly related species.…”

Section: 12mentioning

confidence: 99%

“…15 Wide range of studies have been conducted on Medicago truncatula and Glycine max (GmSEO-F1-F4) regarding SEO-F protein to gain further insight characterizing gene encoding as forisomettes (forisome subunit), which assemble into a special type of crystalloid P-protein unique in Fabaceae. 34 Studies based on heterologous expression it is known that either MtSEO-F1 or MtSEO-F4 expressed individually can assemble into a homomeric protein complex which is similar to the native forisomes with respect to its structure and function. 45 This homomeric protein assembly has a spindle shaped body and longitudinally arranged fibrils and due to its similarity with the native forisomes is often described as the artificial forisomes.…”

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confidence: 99%