Background: Aquaporins, also known as major intrinsic proteins (MIPs), facilitate the
membrane diffusion of water and some other small solutes. The roles of MIPs in plant physiological
processes are established and now their roles in plant-pathogen interactions are getting more
Objective: To investigate the evolution, diversity, and structural insights of Phytophthora MIPs
(PhyMIPs) and to compare them to those in other domains of life.
Methods: Bioinformatics approaches were used to identify and characterize the PhyMIPs. The
phylogenetic analysis was done with MEGA7.0 using maximum likelihood method. The prediction
of transmembrane α-helices was done by using SOSUI and TMpred servers, and that of subcellular
localization was performed with WoLF PSORT and Cello prediction system. The structure
of PhyMIP genes was predicted by GeneMark.hmm ES-3.0 program. The 3D homology models
were generated using the Molecular Operating Environment software and the stereochemical
quality of the templates and models was assessed by PROCHECK. The PoreWalker server was
used to detect and characterize PhyMIP channels from their 3D structural models.
Results: Herein, we identified 17, 24, 27, 19, 19, and 22 full-length MIPs, respectively, in the genomes
of six Phytophthora species, P. infestans, P. parasitica, P. sojae, P. ramorum, P. capsici,
and P. cinnamomi. Phylogenetic analysis showed that the PhyMIPs formed a completely distinct
clade from their counterparts in other taxa and were clustered into nine subgroups. Sequence and
structural properties indicated that the primary selectivity-related constrictions, including aromatic
arginine (ar/R) selectivity filter and Froger's positions in PhyMIPs were distinct from those in other
taxa. The substitutions in the conserved Asn-Pro-Ala motifs in loops B and E of many PhyMIPs
were also divergent from those in other taxonomic domains. The group-specific consensus sequences/
motifs deciphered in different loops and transmembrane α-helices of PhyMIPs were distinct
from those in plants, animals, and other microbes.
Conclusion: This study represents PhyMIPs with distinct evolutionary and structural properties,
and the data collectively indicates that PhyMIPs might have novel functions.