Prediction, Analysis And Functional Identification Of F-Box Proteins In Medicago Truncatula

F-box proteins are subunits of Skpl-Rbxl-Cull-F-box protein (SCF) complex. As one of the largest known families of regulatory proteins in eukaryotes F-box proteins are characterized by a conserved F-box motif (approximately 40-50 amino acids). F-box proteins play a critical role in selective protein degradation by the 26S proteasome, determine the targets and bind to the Skpl (component of the SCF complex). In this study, we predicted and identified 727 putative F-box proteins from Medicago truncatula by using HMMER program with F-box protein motif sequences as queries and Smart/Pfam database. Through the Smart/Pfam database analysis, we show that F-box proteins have several other functional domains in C-terminal, such as LRRs, KELCH, FBA and FBA. Based on the composition of the C-terminal domain, they can be divided into twelve subfamilies. With phylogenetic analysis of the F-box proteins, the F-box proteins can be classified into five major families, and each family can be further classified into multiple subfamilies. We analyzed genomic distribution of F-box protein-encoding genes on Medicago truncatula chromosomes and show that the expansion of F-box protein-encoding genes in Medicago truncatula was probably due to localized gene duplications. Cis-acting element analysis shows that some F-box protein genes are involved in abiotic stress response. By this study, some functions of the F-box proteins can be uncovered.