title: Molecular evolution of miraculin-like proteins in soybean Kunitz super-family.
abstract: Miraculin-like proteins (MLPs) belong to soybean Kunitz super-family and have been characterized from many plant families like Rutaceae, Solanaceae, Rubiaceae, etc. Many of them possess trypsin inhibitory activity and are involved in plant defense. MLPs exhibit significant sequence identity (~30-95%) to native miraculin protein, also belonging to Kunitz super-family compared with a typical Kunitz family member (~30%). The sequence and structure-function comparison of MLPs with that of a classical Kunitz inhibitor have demonstrated that MLPs have evolved to form a distinct group within Kunitz super-family. Sequence analysis of new genes along with available MLP sequences in the literature revealed three major groups for these proteins. A significant feature of Rutaceae MLP type 2 sequences is the presence of phosphorylation motif. Subtle changes are seen in putative reactive loop residues among different MLPs suggesting altered specificities to specific proteases. In phylogenetic analysis, Rutaceae MLP type 1 and type 2 proteins clustered together on separate branches, whereas native miraculin along with other MLPs formed distinct clusters. Site-specific positive Darwinian selection was observed at many sites in both the groups of Rutaceae MLP sequences with most of the residues undergoing positive selection located in loop regions. The results demonstrate the sequence and thereby the structure-function divergence of MLPs as a distinct group within soybean Kunitz super-family due to biotic and abiotic stresses of local environment.
authors.affiliation: Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247 667, India.
authors.forename: Purushotham
authors.initials: P
authors.lastname: Selvakumar
authors.forename: Deepankar
authors.initials: D
authors.lastname: Gahloth
authors.forename: Prabhat Pratap Singh
authors.initials: PP
authors.lastname: Tomar
authors.forename: Nidhi
authors.initials: N
authors.lastname: Sharma
authors.forename: Ashwani Kumar
authors.initials: AK
authors.lastname: Sharma
mesh_terms: D000595:Amino Acid Sequence; D019143:Evolution, Molecular; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D010944:Plants / Q000235:genetics*; D012641:Selection, Genetic; D017386:Sequence Homology, Amino Acid; D030262:Soybean Proteins / Q000235:genetics*; D013025:Glycine max / Q000235:genetics*; D040681:Structural Homology, Protein; D013329:Structure-Activity Relationship; D014360:Trypsin Inhibitor, Kunitz Soybean / Q000235:genetics*
chemical_list: D030262:Soybean Proteins; D014360:Trypsin Inhibitor, Kunitz Soybean