Interaction of phomopsin A with normal and subtilisin-treated bovine brain tubulin.
Tubulin, the major component of microtubules, has a tendency to lose its ability to assemble or to bind to ligands in a time-dependent process known as "decay." The decay process also causes tubulin to expose sulfhydryl groups and hydrophobic areas. The antimitotic drug phomopsin A strongly protects the tubulin molecule from decay. Here we have studied the interaction of phomopsin A with alpha beta tubulin and tubulin which has been treated with subtilisin to remove selectively the C-termini of the alpha and beta chains (alpha(s) beta(s)). The binding of phomopsin A to alpha beta tubulin decreases the sulfhydryl titer by approximately 1.0 mol/mol. Selective removal of the peptides from the C-terminal ends does not affect phomopsin A's interaction with tubulin. Moreover, the alpha(s) beta(s) tubulin-phomopsin A complex appears to be more stable than the alpha bet tubulin-phomopsin A complex as determined by the time-dependent increase in exposure of sulfhydryl groups and hydrophobic areas on tubulin. In fact, phomopsin A inhibits the decay process of alpha(s) beta(s) tubulin completely. This observation raises the possibility of determining the conformation of this configuration of tubulin.
Chaudhuri
A R
AR
Department of Biochemistry, University of Texas Health Science Center, San Antonio 78284-7760, USA.
Ludueña
R F
RF
D000478:Alkylation; D000817:Anilino Naphthalenesulfonates / Q000378:metabolism; D000818:Animals; D001923:Brain Chemistry; D002417:Cattle; D005456:Fluorescent Dyes; D015394:Molecular Structure; D009183:Mycotoxins / Q000737:chemistry / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism; D013381:Subtilisins / Q000378:metabolism / Q000494:pharmacology*; D014404:Tubulin / Q000378:metabolism*; D009842:Oligopeptides
D000817:Anilino Naphthalenesulfonates; D005456:Fluorescent Dyes; D009183:Mycotoxins; D010446:Peptide Fragments; D013381:Subtilisins; D014404:Tubulin; C035763:5,5'-bis(8-(phenylamino)-1-naphthalenesulfonate); C035753:phomopsin; D009842:Oligopeptides