Individual amino acid residues in CLV3 peptide contribute to its stability in vitro

Abstract

CLV3 acts as a peptide ligand to interact with leucine-rich repeat (LRR) receptor kinases in neighboring cells to restrict the size of shoot apical meristems (SAM s) in Arabidopsis. To examine contributions of individual amino acid residues in CLV3 peptide in SAM maintenance, 12 synthetic Ala-substituted CLV3 peptides were applied to clv3-2 seedlings cultured in vitro, and the sizes of SAM s were measured after 9 d. The result exhibited that Pro-9 and His-11 are the most critical residues, while Val-3 and Ser-5 are the least important ones for CLV3 functions in SAM s in vitro. With MA LDI-TO F mass spectrum analyses, we further showed that Ala substitution in His-11 led to a greatly reduced stability of the peptide, leading to a complete degradation of the peptide after cultured with seedlings for only one hour. The substitution of Pro-9 by Ala also led to a complete degradation of the peptides after 2 d incubation. In contrast, Ala substitutions in Val-3 or Ser-5 gave very little changes on peptide stabilities. These results suggested that stabilities of Ala-substituted CLV3 peptides are positively correlated with their activities in SAM s. We thus propose that the stability of CLV3 may partially contribute to its function in SAM maintenance. © 2013 Landes Bioscience.