title: Polygalacturonase-inhibiting proteins--leucine-rich repeat proteins in plant defence.
abstract: Plant polygalacturonase-inhibiting proteins (PGIPs) belong to the leucine-rich repeat (LRR) family and are known to prevent pathogen invasion by inhibiting the plant cell wall degrading enzyme, polygalacturonase. Our study reveals that these multigene-encoded defence proteins found in flowering plants only exhibit identical domain architecture with 10 tandemly-arranged LRRs. This implies that variations of PGIP inhibitory properties are not associated with the number of the repeats but with subtle changes in the sequence content of the repeats. The first and eighth repeat contain more mutations compared to the strict conservation of the plant-specific LRRs or any repeat at other positions. Each of these repeats forms a separate cluster in the phylogenetic tree, both within and across plant families, thus suggesting uniqueness with respect to their position. A study of the genes encoding PGIPs, shows the existence of two categories (i) single exon and hence no intron; and (ii) two exons with an intron in between. Analyses of the intron phase and correlation of the exon-intron structure with the compact structural modules in PGIPs support insertion of introns in the pre-existing single exon genes and thus the intron late model. Lack of conservation of phase across families and formation of individual clusters for each family in the phylogenetic tree drawn with the intron sequences illustrate the event of insertion that took place separately in each of these families.
authors: Department of Biotechnology, School of Biotechnology and Biological Sciences, West Bengal University of Technology, Salt Lake, Kolkata, India.
authors: A
authors: A
authors: Maulik
authors: A I
authors: AI
authors: Sarkar
authors: S
authors: S
authors: Devi
authors: S
authors: S
authors: Basu
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D019143:Evolution, Molecular; D005091:Exons; D017343:Genes, Plant; D007438:Introns; D000090263:Leucine-Rich Repeat Proteins; D019684:Magnoliopsida / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D010802:Phylogeny; D010940:Plant Proteins / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D011096:Polygalacturonase; D011506:Proteins / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D020080:Tandem Repeat Sequences
chemical_list: D000090263:Leucine-Rich Repeat Proteins; C081479:PGIP protein, plant; D010940:Plant Proteins; D011506:Proteins; D011096:Polygalacturonase