PIRLs: A novel class of plant intracellular leucine-rich repeat proteins

• Published in: Plant and cell physiology Vol. 46; no. 6; pp. 913 - 922
• Main Authors: Forsthoefel, N.R.(Whitman Coll., Walla Walla, WA (USA)), Cutler, K, Port, M.D, Yamamoto, T, Vernon, D.M
• Format: Journal Article
• Language: English
• Published: Japan Oxford University Press 01.06.2005; Oxford Publishing Limited (England)
• Subjects: Amino Acid Sequence; amino acid sequences; Amino acids; Arabidopsis; Arabidopsis - chemistry; Arabidopsis - genetics; Arabidopsis Proteins; Arabidopsis Proteins - chemistry; Arabidopsis Proteins - classification; Arabidopsis Proteins - genetics; ARABIDOPSIS THALIANA; Base Sequence; BINDING PROTEINS; chemistry; chromosomes; classification; complementary DNA; DNA, Complementary; DNA, Complementary - genetics; DNA, Plant; DNA, Plant - genetics; EST; Evolution, Molecular; exons; expressed sequence tag; expressed sequence tags; G-proteins; gene expression regulation; Gene knockouts; Gene Targeting; Genes, Plant; GENETIC TRANSFORMATION; genetics; introns; knockout mutants; LEUCINA; LEUCINE; Leucine - chemistry; leucine-rich repeat; Leucine-rich repeats; Linker protein; LRR; messenger RNA; Molecular Sequence Data; Multigene Family; NBS-LRR; nucleotide-binding site-LRR; PGIP; PIRL; plant biochemistry; plant genetics; plant intracellular Ras group-related LRR; plant physiology; plant proteins; polygalacturonase inhibitor protein; PROTEINAS AGLUTINANTES; PROTEINE DE LIAISON; Proteins; RACE; rapid amplification of cDNA ends; reverse transcription–polymerase chain reacion; RT–PCR; sequence analysis; Sequence Homology, Amino Acid; Signal transduction; Tandem Repeat Sequences; transfer DNA; TRANSFORMACION GENETICA; TRANSFORMATION GENETIQUE; Yeasts
• ISSN: 0032-0781; 1471-9053
• DOI: 10.1093/pcp/pci097

Leucine-rich repeat (LRR) proteins feature tandem Introduction leucine-rich motifs that form a protein-protein interaction domain. Plants contain diverse classes of LRR proteins, many of which take part in signal transduction. We have identified a novel family of nine Arabidopsis LRR proteins that, based on predicted intracellular location and LRR motif consensus sequence, are related to Ras-binding LRR proteins found in signaling complexes in animals and yeast. This new class has been named plant intracellular Ras group-related LRR proteins (PIRLs). We have characterized PIRL cDNAS, rigorously defined gene and protein annotations, investigated gene family evolution and surveyed mRNA expression. While LRR regions suggested a relationship to Ras group LRR proteins, outside of their LRR domains PIRLs differed from Ras group proteins, exhibiting N- and C-terminal regions containing low complexity stretches and clusters of charged amino acids. PIRL genes grouped into three subfamilies based on sequence relationships and gene structures. Related gene pairs and dispersed chromosomal locations suggested family expansion by ancestral genomic or segmental duplications. Expression surveys revealed that all PIRL mRNAs are actively transcribed, with three expressed differentially in leaves, roots or flowers. These results define PIRLs as a distinct, plant-specific class of intracellular LRR proteins that probably mediate protein interactions, possibly in the context of signal transduction. T-DNA knock-out mutants have been isolated as a starting point for systematic functional analysis of this intriguing family.