Function of the Cytosolic N-terminus of Sucrose Transporter AtSUT2 in Substrate Affinity

FEBS Lett. 2000 Nov 24;485(2-3):189-94. doi: 10.1016/s0014-5793(00)02180-3.

Abstract

AtSUT2 was found to be a low-affinity sucrose transporter (K(M)=11.7 mM at pH 4). Chimeric proteins between AtSUT2 and the high-affinity StSUT1 were constructed in which the extended N-terminus and central loop of AtSUT2 were exchanged with those domains of StSUT1 and vice versa. Chimeras containing the N-terminus of AtSUT2 showed significantly lower affinity for sucrose compared to chimeras containing the N-terminus of StSUT1. The results indicate a significant function of the N-terminus but not the central cytoplasmic loop in determining substrate affinity. Expression of AtSUT2 in major veins of source leaves and in flowers is compatible with a role as a second low-affinity sucrose transporter or as a sucrose sensor.

MeSH terms

  • Amino Acid Sequence
  • Arabidopsis / chemistry
  • Arabidopsis / genetics
  • Biological Transport
  • Carrier Proteins / chemistry*
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Cytosol / chemistry*
  • Gene Expression
  • Hydrogen-Ion Concentration
  • Kinetics
  • Membrane Transport Proteins*
  • Molecular Sequence Data
  • Peptide Fragments / chemistry
  • Peptide Fragments / genetics
  • Peptide Fragments / metabolism*
  • Plant Proteins / chemistry*
  • Plant Proteins / genetics
  • Plant Proteins / metabolism*
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Saccharomyces cerevisiae / genetics
  • Sucrose / metabolism

Substances

  • Carrier Proteins
  • Membrane Transport Proteins
  • Peptide Fragments
  • Plant Proteins
  • Recombinant Fusion Proteins
  • sucrose transport protein, plant
  • Sucrose