Skip Navigation


MBE Advance Access originally published online on November 1, 2007
Molecular Biology and Evolution 2008 25(1):187-198; doi:10.1093/molbev/msm238
This Article
Right arrow Full Text Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow Supplementary Material
Right arrow Supplementary Material
Right arrowOA All Versions of this Article:
25/1/187    most recent
msm238v2
msm238v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Google Scholar
Right arrow Articles by Tawari, B.
Right arrow Articles by Clark, C. G.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Tawari, B.
Right arrow Articles by Clark, C. G.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

© 2007 The Authors.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Research Articles

Patterns of Evolution in the Unique tRNA Gene Arrays of the Genus Entamoeba

Blessing Tawari*,1,2, Ibne Karim M. Ali*,1,3, Claire Scott*,4, Michael A. Quail{dagger}, Matthew Berriman{dagger}, Neil Hall{dagger},{ddagger},5 and C. Graham Clark*

* Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
{dagger} The Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
{ddagger} The Institute for Genomic Research, 9712 Medical Center Drive, Rockville, Maryland

E-mail: graham.clark{at}lshtm.ac.uk.

Accepted for publication October 27, 2007.

Genome sequencing of the protistan parasite Entamoeba histolytica HM-1:IMSS revealed that almost all the tRNA genes are organized into tandem arrays that make up over 10% of the genome. The 25 distinct array units contain up to 5 tRNA genes each and some also encode the 5S RNA. Between adjacent genes in array units are complex short tandem repeats (STRs) resembling microsatellites. To investigate the origins and evolution of this unique gene organization, we have undertaken a genome survey to determine the array unit organization in 4 other species of Entamoeba—Entamoeba dispar, Entamoeba moshkovskii, Entamoeba terrapinae, and Entamoeba invadens—and have explored the STR structure in other isolates of E. histolytica. The genome surveys revealed that E. dispar has the same array unit organization as E. histolytica, including the presence and numerical variation of STRs between adjacent genes. However, the individual repeat sequences are completely different to those in E. histolytica. All other species of Entamoeba studied also have tandem arrays of clustered tRNA genes, but the gene composition of the array units often differs from that in E. histolytica/E. dispar. None of the other species’ arrays exhibit the complex STRs between adjacent genes although simple tandem duplications are occasionally seen. The degree of similarity in organization reflects the phylogenetic relationships among the species studied. Within individual isolates of E. histolytica most copies of the array unit are uniform in sequence with only minor variation in the number and organization of the STRs. Between isolates, however, substantial differences in STR number and organization can exist although the individual repeat sequences tend to be conserved. The origin of this unique gene organization in the genus Entamoeba clearly predates the common ancestor of the species investigated to date and their function remains unclear.

Key Words: Entamoeba • tRNA genes • repeated DNA, recombination

1 Equal contribution to this work.

2 Present address: Bayer Schering Pharma, Strawberry Hill, RG14 1JA, United Kingdom.

3 Present address: Division of Infectious Diseases and International Health, University of Virginia Health System.

4 Present address: Queen Mary's School of Medicine and Dentistry, Institute of Cell and Molecular Science, Centre for Cutaneous Research, Whitechapel, London, United Kingdom.

5 Present address: School of Biological Sciences, University of Liverpool, Biosciences Building, Liverpool, United Kingdom.

Laura Katz, Associate Editor


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?


This article has been cited by other articles:


Home page
 Am J Trop Med HygHome page
O. Valenzuela, P. Moran, F. Ramos, J. I. Cardoza, G. Garcia, A. Valadez, L. Rojas, A. Garibay, E. Gonzalez, and C. Ximenez
Two Different Chitinase Genotypes in a Patient with an Amebic Liver Abscess: A Case Report
Am J Trop Med Hyg, January 1, 2009; 80(1): 51 - 54.
[Abstract] [Full Text] [PDF]


Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.