In silico characterization of MTP1 gene associated with Zn homeostasis across different dicot plant species

ABSTRACTZinc (Zn) is tightly regulated in plants. The MTP1/ZAT (metal tolerance protein) plays a critical role in adjusting Zn homeostasis upon Zn fluctuation in plants. This study characterizes MTP1 homologs with particular emphasis on AtMT1 in various dicot plants. The protein BLAST search was used to identify a total of 21 MTP1 proteins. Generally, all these MTP1 proteins showed around 400 residues long, six transmembrane helices, stable instability index along with cation transmembrane transporter activity (GO:0008324). These physio-chemical features of MTP1 can be utilized as a benchmark in the prediction of Zn uptake and tolerance in plants. These MTP1 homologs were located on chromosomes 2, 7, and 14 with one exon. Motif analysis showed conserved sequences of 41-50 residues belonging to the family of cation efflux, which may be helpful for binding sites targeting and transcription factor analysis. Phylogenetic studies revealed close similarities of AtZAT with Glycine max and Medicago trunculata that may infer a functional relationship in Zn tolerance or uptake across different plant species. Further, interactome analysis suggests that AtZAT is closely linked cadmium/zinc-transporting ATPase and ZIP metal ion transporter, which could provide essential background for functional genomics studies in plants. The network of AtZAT is predominantly connected to cadmium/zinc-transporting ATPase (HMA2, HMA3, HMA4), cation efflux protein (MTP11), and metal tolerance protein C3 (AT4G58060). The Genevestigator platform further predicts the high expression potential of AtMTP1 in root tissue at the germination and grain filling stage. The structural analysis of MTP1 proteins suggests the conserved N-glyco motifs as well as similar hydrophobicity, net charge and nonpolar residues, alpha-helix in all MTP1 proteins. Altogether, these in silico characterization features of MTP1 and its orthologs will provide an essential theoretical background to perform wet-lab experiments and to better understand Zn homeostasis aiming to develop genetically engineered plants.

Identification and characterization of a tobacco metal tolerance protein, NtMTP2

Metal Tolerance Protein 2 from N. tabacum (NtMTP2) is a tonoplast-localized Co and Ni efflux transporter. As an housekeeping protein controls optimal micronutrients concentration in the cytoplasm, and sequesters metal excess specifically in leaves.