Uncovering ancient transcription systems with a novel evolutionary indicator

Area of Science:

• Molecular Biology
• Evolutionary Biology
• Genetics

Background:

• TATA-binding protein (TBP) and Transcription Factor IIB (TFIIB) are crucial, conserved transcription initiation factors in archaea and eukaryotes.
• Understanding their ancestral genes is key to deciphering the evolutionary origins of the RNA polymerase II transcription apparatus.
• Current evolutionary analyses often require excluding gene subsets as an outgroup, limiting comprehensive ancestral reconstruction.

Purpose of the Study:

• To develop an innovative evolutionary analysis method that bypasses the need for an outgroup.
• To elucidate the evolutionary history and ancestral properties of TBP and TFIIB.
• To gain insights into the early evolution of the RNA polymerase II transcription system.

Main Methods:

• Proposed a novel evolutionary analysis concept utilizing intramolecular direct repeat similarities within TBP and TFIIB.
• Applied this method to analyze nucleotide sequences of contemporary archaeal and eukaryotic TBP and TFIIB genes.
• Used sequence similarity as an evolutionary measure to infer ancestral relationships and gene emergence order.

Main Results:

• Successfully revealed the degree of similarity between extant TBP/TFIIB genes and their ancestors.
• Provided information on the properties of ancestral TBP and TFIIB.
• Determined the order of emergence of TBP and TFIIB during evolution.

Conclusions:

• Early transcription systems likely required RNA polymerase II interaction and activity regulation before precise enzyme positioning.
• The proposed method offers a quantitative approach to studying mechanistic and system evolution.
• This research provides a new perspective on the fundamental origins of eukaryotic transcription.