Mobile self-splicing introns and inteins as environmental sensors

Abstract

Self-splicing introns and inteins are often mobile at the level of the genome. Although these RNA and protein elements, respectively, are generally considered to be selfish parasites, group I and group II introns and inteins can be triggered by environmental cues to splice and/or to mobilize. These cues include stressors such as oxidizing agents, reactive oxygen and nitrogen species, starvation, temperature, osmolarity and DNA damage. Their sensitivity to these stimuli leads to a carefully choreographed dance between the mobile element and its host that is in tune with the cellular environment. This responsiveness to a changing milieu provides strong evidence that these diverse, self-splicing mobile elements have adapted to react to prevailing conditions, to the potential advantage of both the element and its host.

The yeast mating-type switching endonuclease HO is a domesticated member of an unorthodox homing genetic element family

“…FBA1 can be described as the host gene for the WHO element, even though the element lies downstream of FBA1 rather than interrupting it. This structural organization makes WHO elements different from the two currently recognized classes of homing genetic elements, which are inteins and intron-encoded homing endonucleases (Belfort et al, 2005; Belfort, 2017). In both of these other classes the homing element is a self-splicing entity, transcribed as an internal part of the host gene, that must be removed to make the mature host protein.…”

“…In phylogenetic and other sequence similarity analyses, the two yeast proteins HO and VDE were found to be each other’s closest relatives (Dalgaard et al, 1997; Koufopanou and Burt, 2005; Green et al, 2018). Although HO is related to inteins, and more distantly related to other homing endonucleases in the LAGLIDADG superfamily (Chevalier and Stoddard, 2001), it is an independently expressed standalone gene, whereas inteins and other homing endonucleases are self-splicing entities embedded within their host genes (Belfort et al, 2005; Belfort, 2017). HO does not undergo protein splicing and has no exteins.…”

The crystal structure of the naturally split gp41‐1 intein guides the engineering of orthogonal split inteins from cis‐splicing inteins

“…). Inteins are commonly regarded as selfish parasitic elements, albeit some evidence attributes a regulatory role in controlling the activity of host proteins in response to environmental cues triggering the splicing reaction .…”

The crystal structure of the naturally split gp41-1 intein guides the engineering of orthogonal split inteins from acis-splicing intein

“…1). Inteins are commonly regarded as selfish parasitic elements, albeit some evidence attributes a regulatory role in controlling the activity of host proteins in response to environmental cues triggering the splicing reaction 3,5 . During recent years, inteins have become increasingly popular for diverse applications in biotechnology, chemical biology, and synthetic biology because of the following properties.…”