Rational design of allosteric ribozymes

Area of Science:

• Biochemistry
• Molecular Biology
• Synthetic Biology

Background:

• Cellular processes rely on metabolic pathway control, often achieved through allosteric regulation of protein enzymes.
• While RNA molecules (ribozymes) catalyze reactions, true allosteric regulation analogous to protein enzymes has not been observed.
• Recent advances show RNA can form specific small-molecule receptors (aptamers).

Purpose of the Study:

• To investigate if ribozyme catalytic activity can be controlled by effector molecules.
• To design and create conjoined aptamer-ribozyme complexes for allosteric regulation.
• To establish the first example of an allosteric ribozyme.

Main Methods:

• Conjoining an ATP-binding RNA aptamer to a self-cleaving ribozyme.
• Assessing the catalytic rate of the construct in the presence of various nucleotides.
• Introducing mutations in the aptamer domain to evaluate the specificity and mechanism of allosteric control.

Main Results:

• The first allosteric ribozyme was created, showing ATP-specific control over catalytic rate.
• A 180-fold reduction in catalytic rate was observed with adenosine or ATP, but not other nucleotides.
• Mutations disrupting ATP binding or altering aptamer-ribozyme proximity abolished allosteric control.
• Allosteric hammerhead ribozymes activated by ATP and a theophylline-controlled ribozyme were also developed.

Conclusions:

• Catalytic RNAs can be regulated via allosteric mechanisms, similar to protein enzymes.
• Rational design strategies enable the engineering of novel catalytic polynucleotides with effector-controlled rates.
• This work opens possibilities for creating precisely regulated RNA-based molecular systems.