Whole-genome comparison of leucine-rich repeat extensins in Arabidopsis and rice. A conserved family of cell wall proteins form a vegetative and a reproductive clade.
We have searched the Arabidopsis and rice (Oryza sativa) genomes for homologs of LRX1, an Arabidopsis gene encoding a novel type of cell wall protein containing a leucine-rich repeat (LRR) and an extensin domain. Eleven and eight LRX (LRR/EXTENSIN) genes have been identified in these two plant species, respectively. The LRX gene family encodes proteins characterized by a short N-terminal domain, a domain with 10 LRRs, a cysteine-rich motif, and a variable C-terminal extensin-like domain. Phylogenetic analysis performed on the conserved domains indicates the existence of two major clades of LRX proteins that arose before the eudicot/monocot divergence and then diversified independently in each lineage. In Arabidopsis, gene expression studies by northern hybridization and promoter::uidA fusions showed that the two phylogenetic clades represent a specialization into "reproductive" and "vegetative" LRXs. The four Arabidopsis genes of the "reproductive" clade are specifically expressed in pollen, whereas the seven "vegetative" genes are predominantly expressed in various sporophytic tissues. This separation into two expression classes is also supported by previous studies on maize (Zea mays) and tomato (Lycopersicon esculentum) LRX homologs and by information on available rice ESTs. The strong conservation of the amino acids responsible for the putative recognition specificity of the LRR domain throughout the family suggests that the LRX proteins interact with similar ligands.
Baumberger
Nicolas
N
Institute of Plant Biology, University of Zurich, CH-8008 Zurich, Switzerland.
Doesseger
Brigitte
B
Guyot
Romain
R
Diet
Anouck
A
Parsons
Ronald L
RL
Clark
Mark A
MA
Simmons
M P
MP
Bedinger
Patricia
P
Goff
Stephen A
SA
Ringli
Christoph
C
Keller
Beat
B
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism*; D017124:Conserved Sequence / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D018745:Genome, Plant; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism; D000090263:Leucine-Rich Repeat Proteins; D019684:Magnoliopsida / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics; D012275:Oryza / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D012098:Reproduction / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
D029681:Arabidopsis Proteins; D006023:Glycoproteins; C427476:LRX1 protein, Arabidopsis; D000090263:Leucine-Rich Repeat Proteins; D010940:Plant Proteins; D011506:Proteins; C005488:extensin protein, plant