Repeat sequence families derived from mammalian tRNA genes

Area of Science:

• Genomics
• Molecular Evolution
• Bioinformatics

Background:

• Short interspersed repetitive DNA sequences (SINEs) are abundant in mammalian genomes.
• SINEs possess RNA polymerase III promoters, potentially aiding their transposition via an RNA intermediate.
• The evolutionary origins of many SINE families remain unclear.

Purpose of the Study:

• To investigate the relationship between SINEs and transfer RNA (tRNA) genes in mammals.
• To determine if SINE promoter regions are derived from tRNA genes.
• To explore the evolutionary origins of SINE families in the prosimian Galago crassicaudatus.

Main Methods:

• Sequence comparison analysis of SINE families from Galago crassicaudatus, rats, and mice.
• Homology assessment between SINE sequences and human methionine tRNA genes.
• Comparative genomics to identify evolutionary relationships.

Main Results:

• Galago monomer and type II SINE families exhibit 68% and 62% homology, respectively, to human methionine tRNA.
• Rat identifier and mouse B2 SINE families show close sequence relationships to alanine and serine tRNA genes.
• Identified significant sequence similarities between various mammalian SINEs and tRNA genes.

Conclusions:

• Mammalian SINEs, particularly their promoter regions, are likely derived from transfer RNA (tRNA) genes.
• Many SINE families represent amplified tRNA pseudogenes.
• This finding provides insight into the evolutionary mechanisms driving the amplification of repetitive DNA elements in mammalian genomes.