http://hdl.handle.net/10366/156462 2026-04-24T05:54:44Z http://hdl.handle.net/10366/166999 Arabinogalactan proteins (AGPs) are involved in various physiological processes, such as cell elongation, xylem differentiation, resistance to abiotic stresses or secretion and adherence of seed coat mucilage, a structure suggested as a model system for cell wall studies. The specific roles of AGPs are not fully established, although their carbohydrate motif (type II arabinogalactan, AGII) seems to be essential, being able to mediate interactions with different signalling molecules or with other cell wall polysaccharides. The aim of the present work is to determine the role of AGII from AGPs in the structural organization of the cell wall, using Arabidopsis thaliana plants that overproduce β-galactosidase βV-Gal from Cicer arietinum (35S::βV-Gal plants), an enzyme that acts specifically on the β-(1,3) and β-(1,6)-galactosyl bonds of AGII. The characterization of the seed coat mucilage has allowed us to establish a cell wall homeostasis mechanism in which the neutral side chains of the AGII of the AGPs determine the degree of HG methyl esterification. Thus, the reduction in the galactose is accompanied by an increase in the level of esterification, probably as a compensatory mechanism to maintain the mechanical properties of this specialized cell wall and its hydration properties. 2025-01-01T00:00:00Z http://hdl.handle.net/10366/166998 [EN] Proteins of the PF10950 family feature the DUF2775 domain of unknown function. The most studied are specific tissue (ST) proteins with tandem repeats, which are putative precursors of cyclopeptide alkaloids. Here, we study uncharacterised short ST (SST) proteins with the DUFF2775 domain by analysing 194 sequences from 120 species of 39 taxonomic families in silico. SST proteins have a signal peptide and their size and several other characteristics depend on their individual taxonomic family. Sequence analyses revealed that SST proteins contain two well-conserved regions, one resembling the ST repeat, which could constitute the core of cyclopeptide alkaloids. We studied the unique SST1 gene of Arabidopsis thaliana, which is adjacent to and co-expressed with a gene encoding a protein with a BURP domain, associated with cyclopeptide production. The empirical analysis indicated that the SST1 promoter is mainly activated in the roots, where most of the transcripts accumulate, and that the SST1 protein accumulates in the root vascular cambium. At the cellular level, SST fused to GFP appears in vesicles that colocalise with the endoplasmic reticulum and the vacuole. Thus, SSTs are a new type of PF10950 protein found in core eudicots with two conserved regions that could be involved in root biology. 2025-04-01T00:00:00Z http://hdl.handle.net/10366/159764 2024-01-01T00:00:00Z http://hdl.handle.net/10366/157631 The Electronic Plant Gene Register 1999-01-01T00:00:00Z http://hdl.handle.net/10366/157630 The Electronic Plant Gene Register 1999-01-01T00:00:00Z http://hdl.handle.net/10366/157629 The Electronic Plant Gene Register 1998-01-01T00:00:00Z http://hdl.handle.net/10366/157628 The Electronic Plant Gene Register 1998-01-01T00:00:00Z http://hdl.handle.net/10366/157627 The Electronic Plant Gene Register 1998-01-01T00:00:00Z http://hdl.handle.net/10366/157626 The Electronic Plant Gene Register 1998-01-01T00:00:00Z http://hdl.handle.net/10366/157625 The Electronic Plant Gene Register 1998-01-01T00:00:00Z http://hdl.handle.net/10366/157624 The Electronic Plant Gene Register 1998-01-01T00:00:00Z http://hdl.handle.net/10366/157623 The Electronic Plant Gene Register 1998-01-01T00:00:00Z http://hdl.handle.net/10366/157591 The Electronic Plant Gene Register 1998-01-01T00:00:00Z http://hdl.handle.net/10366/157394 The protein extracted from the cell wall of the epicotyls of Cicer arietinum L. cv. Castellana was separated by ion exchange chromatography in four different fractions with beta-D-galactosidase (EC 3.2.1.23) activity. These were called betaI, betaII, betaIII and betaIV, according to their order of elution.betaII was associated with a particularly high beta-D-glucosidase (EC 3.2.1.21) activity. Gel filtration chromatography of each of the fractions gave further subdivision of fractions betaI and betaIII. Subfractions 1 betaI, 1 betaII and betaIV have glucosidase activity and subfractions 2 betaI and 2 betaIII have galactosidase activity. The studies on the hydrolytic capacity of these fractions and its relationship with the autolytic process seem to show that subfraction 2 betaIII is responsible for autolysis. The release of total and reducing sugars is very similar for autolysis and hydrolysis by 2 betaIII. The sugars released are mainly galactose and, to a lesser extent arabinose and glucose. Galactose is released as a monosaccharide, while arabinose remains associ­ated to a polysaccharide componen! together with glucose and small amounts of galactose. 1989-01-01T00:00:00Z http://hdl.handle.net/10366/157393 Two protein fractions with activity as a-galactosidase (EC 3.2.1.22) and a-arabinosi­dase (EC 3.2.1.55), respectively, were identified in the proteins of cell wall of Cicer arietinum L. cv. Castellana extracted with 3 M LiCI. These fractions were partially purified by gel filtration chromatography (Bio Gel P-150), increasing the specific arabinosidase activity 57-fold and the a-galactosidase activity 6-fold. Other protein fractions with glucosidase (EC 3.2.1.21) and glucanase (EC 3.2.1.6) activity also appeared. According to earlier authors, a-arabinosidases and a-galactosidases are related to alterations in linkages occurring in cell walls, since the enzymes are able to hydrolyze isolated wall polymers. However, our preparations hydrolyze intact cell walls only to a very limited extent, such that their participation in the autolytic processes of cell walls can be ruled out. 1989-01-01T00:00:00Z http://hdl.handle.net/10366/157392 During the growth of Cicer arietinum epicotyls an increase in specific cell wall beta-glucosidase and beta-galactosidase activities were observed. In contrast, the amount of cell wall proteins extracted with 3 M LiCI decreased between the third and the fourth day of germination, remaining constant up to the seventh day. Partial purification of the cell wall protein extracts from different days by SP­-Sephadex chromatography showed that one fraction increased both in the amount of protein and beta-galactosidase activity throughout the growth of epicotyls. This protein fraction, which is the third beta-galactosidase (betaIII) eluted from a SP-Sephadex chromatography, has been previously characterized by us as the main enzyme involved in the autolytic process. 1990-01-01T00:00:00Z