Skip to main content Accessibility help
×
Hostname: page-component-7b7567c8c-mnklg Total loading time: 0 Render date: 2026-11-12T15:21:53.921Z Has data issue: false hasContentIssue false

4 - Mobile introns and retroelements in bacteria

Published online by Cambridge University Press:  06 August 2009

Steven Zimmerly
Affiliation:
Department of Biological Sciences, University of Calgary
Peter Mullany
Affiliation:
University College London
Get access

Summary

Introns and retroelements are hallmarks of eukaryotic genomes, but they are also found in bacteria. Here the different types of bacterial introns and retroelements are summarized, including group I introns, group II introns, archaeal bulge-helix-bulge (BHB) introns, intervening sequences (IVSs) in rRNAs, retrons, and diversity generating elements (DGRs). Except for the retroelements, these elements are evolutionarily unrelated, but nevertheless share intriguing properties. The elements all appear mobile within and among bacterial genomes, and in general, do not have clear phenotypic consequence to their host cells. It is possible that introns and retroelements spread from bacteria to eukaryotes as selfish DNAs or were present in the common ancestor of bacteria and eukaryotes.

INTRODUCTION

Introns and retroelements are typically considered components of eukaryotic genomes, because they were discovered in eukaryotes and are particularly abundant in higher eukaryotes. The human genome, for example, contains roughly 200,000 introns and nearly 3 million retroelements (including SINEs), dwarfing the number of functional genes, which are estimated at 30,000 (International Human Genome Sequencing Consortium, 2001). Together, introns and retroelements make up nearly half of the human genome and constitute the major types of “junk DNAs.”

In bacteria, the major types of “junk DNAs” are transposons and prophages, which can constitute anywhere from <1% to 7% of a genome (e.g., Glaser et al., 2001). Introns and retroelements are comparatively rare in bacteria, but they have generated substantial interest because of their parallels to eukaryotic introns and retroelements.

Information

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Book purchase

Temporarily unavailable

Save book to Kindle

To save this book to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.

Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

Available formats
×

Save book to Dropbox

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.

Available formats
×

Save book to Google Drive

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

Available formats
×