Identification of a putative sordarin binding site in Candida albicans elongation factor 2 by photoaffinity labeling.
Candida albicans EF-2 binds sordarin to a single class of binding sites with K(d) = 1.26 microm. Equimolar mixtures of EF-2 and ribosomes, in the presence of a non-hydrolyzable GTP analog, reveal two classes of high affinity sordarin binding sites with K(d) = 0.7 and 41.5 nm, probably due to the existence of two ribosome populations. Photoaffinity labeling of C. albicans EF-2 in the absence of ribosomes has been performed with [(14)C]GM258383, a photoactivatable sordarin derivative. Labeling is saturable and can be considered specific, because it can be prevented with another sordarin analog. The fragment Gln(224)-Lys(232) has been identified as the modified peptide within the EF-2 sequence, Lys(228) being the residue to which the photoprobe was linked. This fragment is included within the G"-subdomain of EF-2. These results are discussed in the light of the high sordarin specificity toward fungal systems.
Domínguez
J M
JM
Research Department, GlaxoSmithKline S. A. PTM, C/Severo Ochoa 2, 28760 Tres Cantos, Madrid, Spain. juan_m_dominguez@gsk.com
Martin
J J
JJ
D000595:Amino Acid Sequence; D000935:Antifungal Agents / Q000378:metabolism*; D001665:Binding Sites; D002176:Candida albicans / Q000378:metabolism*; D007192:Indenes; D008969:Molecular Sequence Data; D020652:Peptide Elongation Factor 2 / Q000737:chemistry* / Q000378:metabolism; D019920:Photoaffinity Labels
D000935:Antifungal Agents; D007192:Indenes; D020652:Peptide Elongation Factor 2; D019920:Photoaffinity Labels; C003329:sordarin