Conserved Motif Identification of Polygalacturonase-inhibiting protein1 (PGIP1) in 19 Species of Plants

Polygalacturonase-inhibiting proteins1 (PGIP1) is a plant protein that plays a crucial role in plant defense against pathogenic microorganisms. Motifs of PGIP1 bind to and block the activity of polygalacturonases, which are enzymes produced by plant pathogens to degrade plant cell walls. The conservation of PGIP1 suggests that it may have a fundamental function in plant biology. Generally, the conserved motif of PGIP1 plays a vital role in plant immunity, development, and stress responses. The identification and characterization of conserved motifs are critical for understanding the molecular mechanisms and evolutionary relationships of proteins. In this research, a total of nineteen PGIP1 protein sequences of eleven different orders in plants (Asterales, Brassicales, Caryophllales, Cucurbitales, Fabales, Malvales, Nymphaeales, Poales, Rosales, Sapindales, and Vitales) were retrieved from NCBI. The motifs of protein sequences were found using the program of Multiple Em for Motif Elicitation (MEME; version 5.5.2) and the Motif Alignment and Search Tool (MAST; version 5.5.2) on the website https://meme-suite.org. A protein conserved motif refers to a specific amino acid sequence pattern that appears in multiple proteins across different species. The parameters of MEME analyses were applied as follows: minimum width for each motif, ten; maximum width for each motif, thirty; maximum number of motifs to find, eight; and number of repetitions, zero or one per sequence. Based on the results, only two motifs (motif 4 and motif 5) were common in all samples:

Motif 4: IPSSLSTLPNLEALHLDRNKLTGTIPESFG

Motif 5: WTNLSGPVPDFLSQLKNLTFLDLSFNNLSG

The width of all motifs was 30aa, except for motifs 6 and 7 with 25 and 21 residues, respectively. Motifs 7, 8, and 6 had the largest E-values among all motifs, which were 3.7e-123, 2.2e-148, and 6.6e-180, respectively.

Motif 7: SLTILDLNHNKIYGSIPVQLT

Motif 8: FKGKVPYLYLSHNQLSGKIPASLGNVDFNR

Motif 6: PYHLASWDPETDCCDWYCVECDDTT

Common conserved motifs among different plant species confirmed PGIP1 protein's functional similarities.