Mobile Genetic Elements and The TmRNA Gene
ssrA is both a target for some mobile DNAs and a passenger on others. It has been found interrupted by three types of mobile elements. By different strategies none of these disrupt gene function: group I introns remove themselves by self-splicing, rickettsial palindromic elements (RPEs) insert in innocuous sites, and integrase-encoding genomic islands split their target ssrA yet restore the split-off portion.
Non-chromosomal ssrA was first detected in a genomic survey of mycobacteriophages (in 10% of the phages). Other mobile elements including plasmids and genomic islands have been found bearing ssrA. One interesting case is Rhodobacter sphaeroides ATCC 17025, whose native tmRNA gene is disrupted by a genomic island; unlike all other genomic islands in tmRNA (or tRNA) genes this island has inactivated the native target gene without restoration, yet compensates by carrying its own tmRNA gene. A very unusual relative of ssrA is found in the lytic mycobacteriophage DS6A, that encodes little more than the TLD.
Read more about this topic: Transfer-messenger RNA
Famous quotes containing the words mobile, genetic and/or elements:
“From three to six months, most babies have settled down enough to be fun but aren’t mobile enough to be getting into trouble. This is the time to pay some attention to your relationship again. Otherwise, you may spend the entire postpartum year thinking you married the wrong person and overlooking the obvious—that parenthood can create rough spots even in the smoothest marriage.”
—Anne Cassidy (20th century)
“What strikes many twin researchers now is not how much identical twins are alike, but rather how different they are, given the same genetic makeup....Multiples don’t walk around in lockstep, talking in unison, thinking identical thoughts. The bond for normal twins, whether they are identical or fraternal, is based on how they, as individuals who are keenly aware of the differences between them, learn to relate to one another.”
—Pamela Patrick Novotny (20th century)
“Kitsch is the daily art of our time, as the vase or the hymn was for earlier generations. For the sensibility it has that arbitrariness and importance which works take on when they are no longer noticeable elements of the environment. In America kitsch is Nature. The Rocky Mountains have resembled fake art for a century.”
—Harold Rosenberg (1906–1978)