TY - JOUR
AU - FELDMAN,, DAVID
AB - An estrogen-binding protein (EBP) has been identified and characterized in the cytosol of the pathogenic yeast Candida albicans. Binding of [3H]estradiol was found to be optimal at pH 7.4 in the presence of 0.3 M KC1 and was linearly related to protein concentration. Binding was very rapid, reaching maximal levels in about 30 min, and was reversible with a dissociation rate constant of 13.2 ± 1.7 x 10-4 sec-1. EBP binding was destroyed by treatment with proteolytic enzymes and by high temperatures. Scatchard analysis of the [3H]estradiol equilibrium binding data of C. albicans (strain stn-1) yielded an apparent dissociation constant of 12.3 _ 2.1 nM and a maximal binding capacity of 753 ± 145 fmol/mg protein. Binding competition experiments showed very high specificity and stereoselectivity of EBP, demonstrating the following order of potency in displacing [3H]estradiol: 17β-estradiol > estrone > estriol > 17α-estradiol. Negligible competitive potency was found for other mammalian steroid hormones, diethylstilbestrol, tamoxifen, or fungal hormones. The abundance of EBP was 4- to 10- fold higher during the early logarithmic growth phase of yeast cells than during the stationary phase. The molecular size of EBP, measured by Sephacryl S-200 gel exclusion chromotography, yielded a Stokes radius of approximately 29 A. Sucrose density gradient sedimentation showed a sedimentation coefficient (S2020,w) of 4, with no ionic dependent aggregation of the [3H]estradiol-EBP complex. The apparent mol wt of the EBP is approximately 46,000, with an axial ratio of 1, indicating the symmetrical shape of the molecule. In summary, in addition to the previously described corticosterone-binding protein, a separate high affinity, stereospecific, estrogen-selective binder has been demonstrated in the cytosol of C. albican (Endocrinology124: 1965-1972,1989) This content is only available as a PDF. Author notes * This work was supported by NIH Grant AI-20409 † To whom all correspondence and requests for reprints should be addressed Copyright © 1989 by The Endocrine Society
TI - Characterization of an Estrogen-Binding Protein in the Yeast Candida albicans
JF - Endocrinology
DO - 10.1210/endo-124-4-1965
DA - 1989-04-01
UR - https://www.deepdyve.com/lp/oxford-university-press/characterization-of-an-estrogen-binding-protein-in-the-yeast-candida-3dPycZ8cpe
SP - 1965
EP - 1972
VL - 124
IS - 4
DP - DeepDyve
ER -