Origin of replication in circular prokaryotic chromosomes

Area of Science:

• Genomics and Molecular Biology
• Bioinformatics
• Evolutionary Biology

Background:

• Prokaryotic chromosome replication origins are crucial for cell division and genome stability.
• Understanding the sequence composition of leading and lagging strands provides clues about replication mechanisms.
• Previous methods for origin prediction were limited in accuracy and scope.

Purpose of the Study:

• To develop a novel method for accurately predicting replication origins in prokaryotic chromosomes.
• To investigate the correlation between DNA strand composition, taxonomic grouping, lifestyle, and replication machinery.
• To explore variations in replication strand bias across different bacterial and archaeal lineages.

Main Methods:

• Analysis of oligomer composition differences between leading and lagging strands in 200 prokaryotic chromosomes.
• Utilizing oligonucleotide composition up to 8 base pairs (bp) to identify strand biases.
• Development of a computational program for precise replication origin localization based on strand asymmetry.

Main Results:

• Oligomer composition differences strongly correlate with taxonomic grouping, lifestyle, and replication polymerase-alpha subunit.
• A universal preference for Guanines (Gs) over Cytosines (Cs) on the leading strand was observed in bacteria.
• The direction of Adenine/Thymine (A/T) skew is determined by the leading strand polymerase-alpha subunit, with variations linked to growth rate and environment.
• Archaea exhibit greater diversity in replication strand skew compared to bacteria.

Conclusions:

• The study presents a robust computational tool for predicting prokaryotic replication origins.
• DNA strand composition analysis offers significant insights into the evolutionary and functional aspects of DNA replication.
• Replication strand bias is a dynamic feature influenced by evolutionary history, environmental factors, and molecular mechanisms.