Abstract
Six conserved, charged amino acids within membrane spans in rice sucrose transporter OsSUT1 were identified using a three-dimensional structural model based on the crystal structures of three major facilitator superfamily (MFS) proteins: LacY, GlpT, and EmrD. These positions in OsSUT1 were selected for mutagenesis and biochemical assays. Among the six mutants, D177N completely lost transport function, D331N retained only a small fraction of sucrose uptake activity (2.3% of that of the wild type), and R335H and E336Q also displayed a substantial decrease in transport activity. D329N functioned as well as wild-type OsSUT1. R188K did not transport sucrose but showed a H(+) leak that was inhibited by sucrose, indicating that R188K had uncoupled sucrose and H(+) translocation. This demonstrates that charged amino acids within membrane spans are important for the transport mechanism of OsSUT1 as they are in lactose permease.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.