Structural basis of transport function in major facilitator superfamily protein from Trichoderma harzianum.
Trichothecenes are the sesquiterpenes secreted by Trichoderma spp. residing in the rhizosphere. These compounds have been reported to act as plant growth promoters and bio-control agents. The structural knowledge for the transporter proteins of their efflux remained limited. In this study, three-dimensional structure of Thmfs1 protein, a trichothecene transporter from Trichoderma harzianum, was homology modelled and further Molecular Dynamics (MD) simulations were used to decipher its mechanism. Fourteen transmembrane helices of Thmfs1 protein are observed contributing to an inward-open conformation. The transport channel and ligand binding sites in Thmfs1 are identified based on heuristic, iterative algorithm and structural alignment with homologous proteins. MD simulations were performed to reveal the differential structural behaviour occurring in the ligand free and ligand bound forms. We found that two discrete trichothecene binding sites are located on either side of the central transport tunnel running from the cytoplasmic side to the extracellular side across the Thmfs1 protein. Detailed analysis of the MD trajectories showed an alternative access mechanism between N and C-terminal domains contributing to its function. These results also demonstrate that the transport of trichodermin occurs via hopping mechanism in which the substrate molecule jumps from one binding site to another lining the transport tunnel.
School of Earth and Environmental Sciences, Central University of Himachal Pradesh, Kangra, Himachal Pradesh, 176206, India.
Nitika
N
Chaudhary
School of Life Sciences, Central University of Himachal Pradesh, Kangra, Himachal Pradesh, 176206, India.
Padmani
P
Sandhu
School of Earth and Environmental Sciences, Central University of Himachal Pradesh, Kangra, Himachal Pradesh, 176206, India. Electronic address: mushtaq.cuhp@gmail.com.
Mushtaq
M
Ahmed
School of Life Sciences, Central University of Himachal Pradesh, Kangra, Himachal Pradesh, 176206, India. Electronic address: yusuf@daad-alumni.de.
Yusuf
Y
Akhter
D001665:Binding Sites; D061046:Biological Control Agents / Q000737:chemistry*; D001692:Biological Transport; D005656:Fungal Proteins / Q000737:chemistry*; D008024:Ligands; D026901:Membrane Transport Proteins / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D010937:Plant Growth Regulators / Q000737:chemistry*; D011485:Protein Binding; D000072417:Protein Domains; D017433:Protein Structure, Secondary; D040681:Structural Homology, Protein; D014242:Trichoderma / Q000737:chemistry* / Q000378:metabolism; D014255:Trichothecenes / Q000737:chemistry*
D061046:Biological Control Agents; D005656:Fungal Proteins; D008024:Ligands; D026901:Membrane Transport Proteins; D010937:Plant Growth Regulators; D014255:Trichothecenes
Bio-control agent; Major facilitator superfamily; Trichoderma spp.; Trichothecene efflux pump