Amplification of a long sequence that includes a processed pseudogene for elongation factor 2 in the mouse

Area of Science:

• Genomics
• Molecular Biology
• Evolutionary Biology

Background:

• Elongation factor 2 (EF2) plays a crucial role in protein synthesis.
• The presence of repetitive DNA sequences in genomes can impact genomic structure and evolution.

Purpose of the Study:

• To investigate the nature and origin of a specific DNA sequence related to EF2 in the mouse genome.
• To understand the amplification and organization of this EF2-related sequence.

Main Methods:

• Quantitative Southern blotting to determine copy number.
• Cosmid cloning and restriction mapping to analyze sequence organization.
• Nucleotide sequencing to assess sequence conservation.
• Pulse-field gel electrophoresis to study large-scale genomic organization.

Main Results:

• Mouse cells contain approximately 70 copies of an EF2-related DNA sequence (MER) per haploid genome.
• MERs exhibit high conservation in restriction maps and nucleotide sequences.
• MERs are likely derived from poly(A)+ mRNA for EF2, integrated, and amplified with flanking sequences.
• Repeating units of MERs are large (over 60 kb), and multiple copies are clustered in specific genomic locations (over 400 kb units).

Conclusions:

• The EF2-related sequence (MER) in mice originated from mRNA and underwent significant amplification and clustering during evolution.
• The conserved nature of MERs suggests a specific mechanism of integration and expansion.
• The large size of repeating units and their clustered arrangement indicate a unique genomic organization.