Nucleotide and DNA uptake by Neurospora crassa: involvement of an uptake stimulating protein.
The basal and DUSF (DNA-uptake-stimulating factor, described previously by Schablik and Szabó (1981) FEMS Microbiol. Lett. 10, 395-397) stimulated uptake of [3H]DNA and radioactive nucleotides by Neurospora crassa (FGSC 1118, slime) cell-wall-less strain was studied. The uptake of [3H]DNA by the cells is a saturable and time-dependent process. The pH and temperature optimum for [3H]DNA uptake are pH 7 and 27 degrees C, respectively. Both basal and DUSF-stimulated uptake of [3H]DNA are inhibited by 2,4-dinitrophenol and iodoacetic acid. The inhibition of the basal uptake of [3H]DNA by cycloheximide is greater than the DUSF-stimulated uptake. The DUSF enhanced not only DNA-uptake but also that of the oligonucleotides and mononucleotides. DUSF binds both macromolecular [3H]DNA and [14C]AMP, and there might be competition between nucleotides and DNA for the binding to DUSF. Polyclonal antibodies prepared against DUSF inhibited both basal and DUSF-enhanced [3H]DNA uptake. DUSF was detected by immunoblotting among the proteins isolated from purified N. crassa cell-membranes. DUSF might be a receptor protein for DNA and nucleotides in the cell-membrane of N. crassa and play a role in DNA and nucleotide uptake.
Tóth
G
G
Institute of Biology, University Medical School of Debrecen, Hungary.
Szabó
G
G
D019297:2,4-Dinitrophenol; D001667:Binding, Competitive; D015153:Blotting, Western; D003513:Cycloheximide / Q000494:pharmacology; D004271:DNA, Fungal / Q000378:metabolism*; D004140:Dinitrophenols / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D005779:Immunodiffusion; D007150:Immunohistochemistry; D007461:Iodoacetates / Q000494:pharmacology; D019807:Iodoacetic Acid; D008565:Membrane Proteins / Q000378:metabolism*; D009492:Neurospora crassa / Q000187:drug effects / Q000378:metabolism*; D009711:Nucleotides / Q000378:metabolism*; D011506:Proteins / Q000494:pharmacology*
D004271:DNA, Fungal; D004140:Dinitrophenols; D007461:Iodoacetates; D008565:Membrane Proteins; D009711:Nucleotides; D011506:Proteins; D003513:Cycloheximide; D019297:2,4-Dinitrophenol; D019807:Iodoacetic Acid