Dr. Ilka Heinemann

photo of Dr. Ilka HeinemannAssociate Professor

Ph.D. Technical University of Braunschweig, Germany
Postdoctoral Fellow, Yale University

Office: Medical Sciences Building Rm. 358
Phone: 519.850.2949
E-mail: ilka.heinemann@uwo.ca
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Research overview

From its transcriptional birth to its death in degradation, an RNA transcript is subject to elaborate control. The cell uses diverse mechanisms to regulate and fine-tune the RNA turnover as a means to control RNA and protein levels. The broad interests of my laboratory are to understand the cellular and molecular mechanisms that control the fate of RNA and the role of polymerases in these processes.


Polyuridylation – a pathway to decay or longevity?

The addition of nucleotides to the 3’end of RNAs has a profound impact on their stability. The untemplated addition of a poly(A)-tail, for example, can either stabilize a transcript or mark it for degradation. A similar, but poorly understood, process known as 3’end uridylation involves the addition of multiple uracil residues to RNA. Poly(U) polymerase substrates are diverse, including pre-mRNA transcripts, mRNAs, transcription start-site-associated RNAs, spliced introns, 3’UTRs, miRNAs, siRNAs and antisense RNAs. Aberrant RNA uridylation and insufficient degradation of polyuridylated RNAs is linked to tumor growth. However, little is known about the targets of RNA uridylation, the respective poly(U) polymerases, the catalytic mechanism, or its biological consequences. We are particularly interested in understanding how polyuridylation contributes to RNA stability and to decipher the biological roles and regulation of RNA 3' uridylation.


Polymerization in the reverse – which way is up?

The small tRNA editing enzyme tRNAHis guanylyltransferase (Thg1) is an essential component in tRNA maturation. Recent structural and biochemical studies revealed that Thg1 contains the same catalytic core as canonical polymerases, but catalyzes a “reverse”, 3’-5’ polymerization reaction. This finding overhauled our perspective of polymerase directionality, thought to be an exclusive “forward” 5’-3’ process. The polymerase active site, or palm domain, can promote both forward and reverse polymerization by the seemingly simple reversal of substrate binding. The ancient emergence of reverse polymerization indicates that a Thg1-like ancestor evolved before the cell was fully committed to forward 5’-3’ nucleotide polymerization for its basic information processes. In our laboratory we are investigating which components determine directionality in polymerases and are engineering polymerases with novel “reverse” capabilities.


Publications

See a complete list of publications from Pubmed.