Final answer:
The helicase activity of TFIIH is essential for separating DNA strands by breaking hydrogen bonds during eukaryotic mRNA transcription and DNA replication, making the DNA template accessible for the synthesis of RNA and new DNA strands.
Step-by-step explanation:
The helicase activity of Transcription Factor IIH (TFIIH) is crucial in the process of eukaryotic transcription. Unlike prokaryotic RNA polymerase, eukaryotic RNA Polymerase II does not have an inherent helicase activity. Therefore, TFIIH, a multi-subunit protein, which contains two subunits with helicase activity, plays an essential role in eukaryotic mRNA transcription. TFIIH functions to separate the two DNA strands of a double helix by breaking the hydrogen bonds between them, making the DNA template accessible for RNA Polymerase II to synthesize RNA.
During DNA replication, TFIIH assists by unwinding the DNA at the origin of replication. This action is necessary because all proteins interacting with DNA need to recognize the specific DNA sequences to which they must bind. By unwinding the DNA, TFIIH allows regulatory proteins and other transcription factors to achieve specific, shape-based interactions with DNA.
If the helicase component of TFIIH is mutated, the DNA strands will not be properly separated, impeding both replication and transcription processes. In replication, helicase's action is complemented by other enzymes such as topoisomerase, which works to relieve the stress on DNA during unwinding, and DNA polymerase, which synthesizes the new DNA strand. Helicase's activity is also interconnected with the work of single-stranded binding proteins, primase, and in later stages, DNA ligase.