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Functionality versus strength - has functional selection taken place in the case of the ecdysteroid receptor response element?

100%

Grad I. , Kochman M. , Ożyhar A.

tom 49

nr 3

747-756

Nuclear receptors are ligand-dependent transcription factors responsible for controlling differentiation, growth and development of higher eukaryotes. Three amino acids within the recognition α-helix of the DNA-binding domain of the nuclear receptors constitute the so-called "P-box" which determines response element specificity. In the ultraspiracle (Usp) protein, which together with EcR forms the heterodimeric ecdysone receptor, the P-box residues are E19, G20 and G23. Substitution of E19, the most characteristic amino acid for estrogen receptor-like P-boxes, with alanine showed that the mutation did not appreciably alter the affinity of the wild-type Usp DNA-binding domain (UspDBDWT) for a probe containing natural ecdysone response element (hsp27wt). Since in many cases E19 contacts a G/C base pair in position -4, which is absent in hsp27wt, we analysed the interaction of UspDBDWT, E19A and other P-box region mutants with the hsp27wt derivative which contains a G/C instead of an T/A base pair in position -4. UspDBDWT exhibited higher affinity for this element than for hsp27wt. Moreover, a different interaction pattern of P-box region mutants was also observed. Thus we conclude that the E19 residue of UspDBD is not involved in any hsp27wt sequence-discerning contacts. However, substitution of the hsp27wt T/A base pair in position -4 with G/C generates target sequence with distinct functional characteristics and possibly with a new specificity. These results could serve as a basis for understanding the role of the presence of a T/A or G/C base-pair in the position -4 in the two types of ecdysone response elements found in nature.

The effect of the juvenile hormone analog, fenoxycarb, on ecdysone receptor B1 expression in the midgut of Bombyx mori during larval-pupal metamorphosis

84%

Goncu E. , Parlak O.

nr 1

Protective role of 20-hydroxyecdysone against lead stress in Chlorella vulgaris cultures

84%

Bajguz A.

tom 01

Kinetic properties of phosphofructokinase and pyruvate kinase in the midgut gland and abdominal muscle of the crayfish Orconectes limosus Raf. [Crustacea: Decapoda] after injections of 20-hydroxyecdysone

67%

Lesicki A.

Biological Bulletin of Poznań

1994

tom 31