The Brassica napus extA extensin gene is expressed in regions of the plant subject to tensile stresses

Shirsat, A. H.; Bell, Adrian D.; Spence, J; Harris, J. N.

doi:10.1007/bf00195195

Cited by 36 publications

(35 citation statements)

References 29 publications

(25 reference statements)

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“…Stress induces specific extensins (Merkouropoulos et al, 1999). There is a correlation between extensin expression and walls that withstand tensile stress such as hypocotyls (Shirsat et al, 1996), seed coats (Cassab et al, 1985), and root hairs that exemplify cells exposed to extremes of osmotic stress; unlike pollen tubes, they possess an abundance of extensin (Bucher et al, 1997). Association of extensins with extension growth is increasingly well documented (Cleland and Karlsnes, 1967;Sadava and Chrispeels, 1973;Roberts and Shirsat, 2006;Gille et al, 2009).…”

Section: What Is the Role Of P3-type Extensin?mentioning

confidence: 99%

Role of the Extensin Superfamily in Primary Cell Wall Architecture

et al. 2011

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Section: What Is the Role Of P3-type Extensin?mentioning

confidence: 99%

Role of the Extensin Superfamily in Primary Cell Wall Architecture

et al. 2011

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“…HRGPs are involved in all aspects of plant growth and development, including wall assembly during embryogenesis (4), and responses to biotic and abiotic stress that include mechanical stress (5), physical wounding (6), pathogenesis (7), and symbiosis (8 -10).…”

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confidence: 99%

Di-isodityrosine Is the Intermolecular Cross-link of Isodityrosine-rich Extensin Analogs Cross-linked in Vitro

Held

Li²,

Kamyab³

et al. 2004

Journal of Biological Chemistry

107

129

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Extensins are cell wall hydroxyproline-rich glycoproteins that form covalent networks putatively involving tyrosyl and lysyl residues in cross-links catalyzed by one or more extensin peroxidases. The precise cross-links remain to be chemically identified both as network components in muro and as enzymic products generated in vitro with native extensin monomers as substrates. However, some extensin monomers contain variations within their putative cross-linking motifs that complicate cross-link identification. Other simpler extensins are recalcitrant to isolation including the ubiquitous P3-type extensin whose major repetitive motif, Ser-(Hyp) 4 -Ser-Hyp-Ser-(Hyp) 4 -Tyr-Tyr-Tyr-Lys, is of particular interest, not least because its Tyr-Tyr-Tyr intramolecular isodityrosine cross-link motifs are also putative candidates for further intermolecular cross-linking to form di-isodityrosine. Therefore, we designed a set of extensin analogs encoding tandem repeats of the P3 motif, including Tyr 3 Phe and Lys 3 Leu variations. Expression of these P3 analogs in Nicotiana tabacum cells yielded glycoproteins with virtually all Pro residues hydroxylated and subsequently arabinosylated and with likely galactosylated Ser residues. This was consistent with earlier analyses of P3 glycopeptides isolated from cell wall digests and the predictions of the Hyp contiguity hypothesis. The tyrosine-rich P3 analogs also contained isodityrosine, formed in vivo. Significantly, these isodityrosine-containing analogs were further crosslinked in vitro by an extensin peroxidase to form the tetra-tyrosine intermolecular cross-link amino acid diisodityrosine. This is the first identification of an intermolecular cross-link amino acid in an extensin module and corroborates earlier suggestions that di-isodityrosine represents one mechanism for cross-linking extensins in muro.Hydroxyproline-rich glycoproteins (HRGPs), 1 which include the extensins, proline-rich proteins, and arabinogalactan proteins (AGPs), contribute to extracellular matrix architecture throughout the plant kingdom and the chlorophycean green algae (1-3). HRGPs are involved in all aspects of plant growth and development, including wall assembly during embryogenesis (4), and responses to biotic and abiotic stress that include mechanical stress (5), physical wounding (6), pathogenesis (7), and symbiosis (8 -10).HRGPs are extended macromolecules consisting of small repetitive peptide and glycopeptide motifs that form peptide modules and glycomodules of functional significance, as in "mix-and-match" mode they define the molecular properties of the overall macromolecule. The glycomodules result from a combination of post-translational modifications unique to plants, namely proline hydroxylation (11) and its subsequent glycosylation (12) that leads either to short arabino-oligosaccharide or larger arabinogalactan polysaccharide addition to the Hyp residues. A sequence-dependent O-Hyp glycosylation code directs the addition of oligosaccharide and polysaccharides (13), and it is likely that...

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“…Extensins contain Ser-Hyp 4 pentapeptide repeats, which are glycosylated by galactose and arabinosyl side chains (Wilson and Fry 1986). Extensin gene expression is induced or up-regulated in tissues under tensile stress (Shirsat et al 1996), strong mechanical pressure (Keller and Lamb 1989), upon wounding (Wycoff et al 1995), and pathogen infection (Garcia-Muniz et al 1998). Subsequent protein insolubilization has been interpreted as a mechanism to strengthen the cell wall in which an increased resistance is required (Fry 1986).…”

mentioning

confidence: 99%

The chimeric leucine-rich repeat/extensin cell wall protein LRX1 is required for root hair morphogenesis inArabidopsis thaliana

Baumberger¹,

Ringli²,

Keller³

2001

Genes Dev.

245

223

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In plants, the cell wall is a major determinant of cell morphogenesis. Cell enlargement depends on the tightly regulated expansion of the wall, which surrounds each cell. However, the qualitative and quantitative mechanisms controlling cell wall enlargement are still poorly understood. Here, we report the molecular and functional characterization of LRX1, a new Arabidopsis gene that encodes a chimeric leucine-rich repeat/extensin protein. LRX1 is expressed in root hair cells and the protein is specifically localized in the wall of the hair proper, where it becomes insolubilized during development. lrx1-null mutants, isolated by a reverse-genetic approach, develop root hairs that frequently abort, swell, or branch. Complementation and overexpression experiments using modified LRX1 proteins indicate that the interaction with the cell wall is important for LRX1 function. These results suggest that LRX1 is an extracellular component of a mechanism regulating root hair morphogenesis and elongation by controlling either polarized growth or cell wall formation and assembly.

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The Brassica napus extA extensin gene is expressed in regions of the plant subject to tensile stresses

Cited by 36 publications

References 29 publications

Role of the Extensin Superfamily in Primary Cell Wall Architecture

Role of the Extensin Superfamily in Primary Cell Wall Architecture

Di-isodityrosine Is the Intermolecular Cross-link of Isodityrosine-rich Extensin Analogs Cross-linked in Vitro

The chimeric leucine-rich repeat/extensin cell wall protein LRX1 is required for root hair morphogenesis inArabidopsis thaliana

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