Nutrient Transport - Exercise #5

You are studying nutrient uptake in E. coli and are curious about a transporter that transports putrescine and ornithine.  The gene for this transporter is potE.

  1. What molecule(s) does this transporter transport into the cytosol and/or periplasmic space?  Establish what category (Passive Diffusion, Facilitated Diffusion, Active Transport).  Establish what class/classes (Ion Driven - be specific, Group Translocation, ABC Transporter) of transporters it belongs to.  What energy source(s), if any, drives the uptake process?

  3. What is the affinity of this transporter for its transported molecule(s)?

  5. Is the transcription of the transporter gene regulated?  If so, what protein(s) regulate it?

  7. Which two amino acid residues (sequence number and amino acid) are thought to be responsible for putrescine uptake? 

  9. Is this gene part of an operon?  If so, what other gene(s) is/are in the operon?  Give the gene function also, if applicable (Hint: click on the genome browser)