Inactivation of Saccharomyces cerevisiae sulfate transporter Sul2p: use it and lose it

Biophys J. 2012 Feb 22;102(4):768-76. doi: 10.1016/j.bpj.2012.01.005. Epub 2012 Feb 21.


Saccharomyces cerevisiae SO(4)(=) transport is regulated over a wide dynamic range. Sulfur starvation causes ∼10,000-fold increase in the (35)SO(4)(=) influx mediated by transporters Sul1p and Sul2p; >80% of the influx is via Sul2p. Adding methionine to S-starved cells causes a 50-fold decline (t(1/2) ∼5 min) in SUL1 and SUL2 mRNA but a slower decline (t(1/2) ∼1 h) in transport. In contrast, SO(4)(=) addition does not affect mRNA but causes a rapid (t(1/2) = 2-4 min) decrease in transport. In met3Δ cells (unable to metabolize SO(4)(=)), addition of SO(4)(=) to S-starved cells causes inactivation of (35)SO(4)(=) influx over times in which cellular SO(4)(=) contents are nearly constant. The relationship between cellular SO(4)(=) and transport inactivation shows that cellular SO(4)(=) is not the signal for Sul2p inactivation. Instead, the transport inactivation rate has the same dependence on extracellular SO(4)(=) as (35)SO(4)(=) influx, indicating that Sul2p exhibits use-dependent inactivation; the transport process itself increases the probability of Sul2p inactivation and degradation. In addition, there is a transient efflux of SO(4)(=) shortly after adding >0.02 mM SO(4)(=) to S-starved met3Δ cells. This transient efflux provides further protection against excessive SO(4)(=) influx and may represent an alternate transport mode of Sul2p.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Anion Transport Proteins / metabolism*
  • Cytosol / metabolism
  • Feedback, Physiological
  • Kinetics
  • Protein Transport
  • Saccharomyces cerevisiae / cytology
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Sulfate Transporters
  • Sulfates / metabolism*


  • Anion Transport Proteins
  • SUL1 protein, S cerevisiae
  • SUL2 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Sulfate Transporters
  • Sulfates