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Cyclic diguanylic acid behaves as a host molecule for planar intercalators
Y C Liaw1, Y G Gao, H Robinson
1Department of Physiology and Biophysics, University of Illinois, Urbana 61801.
FEBS Letters
|May 21, 1990
Summary
Cyclic ribodiguanylic acid (c-(GpGp)), a regulator of cellulose synthase, forms dimers with unique metal-binding properties. This cyclic dinucleotide displays unusual spectral characteristics and interacts with intercalators, suggesting a cage-like binding model.
Area of Science:
- Biochemistry
- Structural Biology
- Crystallography
Background:
- Cyclic ribodiguanylic acid (c-(GpGp)) is an endogenous effector regulating cellulose synthase.
- Understanding the structure of c-(GpGp) is crucial for elucidating its biological functions.
Purpose of the Study:
- To determine the three-dimensional structure of c-(GpGp) in different crystal forms.
- To investigate the metal coordination mechanisms and spectral properties of c-(GpGp).
- To propose a model for c-(GpGp) interactions with planar intercalator molecules.
Main Methods:
- X-ray diffraction analysis at 1 Å resolution.
- Determination of crystal structures in tetragonal and trigonal forms.
- Spectroscopic analysis of c-(GpGp) properties.
Main Results:
- Two distinct crystal structures of c-(GpGp) (tetragonal and trigonal) were determined.
- c-(GpGp) forms self-intercalated dimers, with a hydrated cobalt ion coordinating to adjacent guanines in the tetragonal form.
- Unusual spectral properties were observed, distinct from other cyclic dinucleotides.
- c-(GpGp) interacts with planar intercalators similarly to double helical DNA.
Conclusions:
- The structure reveals a metal coordination mechanism potentially relevant to anticancer drugs like cisplatin.
- A cage-like model of a tetrameric c-(GpGp) aggregate is proposed, featuring a cavity for binding planar intercalators.
- These findings provide new insights into the structural and functional roles of c-(GpGp).