Genome and phylogenetic analyses of trypanosoma evansi reveal extensive similarity to T. brucei and multiple independent origins for dyskinetoplasty

Jason Carnes, Atashi Anupama, Oliver Balmer, Andrew Jackson, Michael Lewis, Rob Brown, Igor Cestari, Marc Desquesnes, Claire Gendrin, Christiane Hertz-Fowler, Hideo Imamura, Alasdair Ivens, Luděk Kořený, De Hua Lai, Annette MacLeod, Suzanne M. McDermott, Chris Merritt, Severine Monnerat, Wonjong Moon, Peter MylerIsabelle Phan, Gowthaman Ramasamy, Dhileep Sivam, Zhao Rong Lun, Julius Lukeš, Ken Stuart*, Achim Schnaufer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Two key biological features distinguish Trypanosoma evansi from the T. brucei group: independence from the tsetse fly as obligatory vector, and independence from the need for functional mitochondrial DNA (kinetoplast or kDNA). In an effort to better understand the molecular causes and consequences of these differences, we sequenced the genome of an akinetoplastic T. evansi strain from China and compared it to the T. b. brucei reference strain. The annotated T. evansi genome shows extensive similarity to the reference, with 94.9% of the predicted T. b. brucei coding sequences (CDS) having an ortholog in T. evansi, and 94.6% of the non-repetitive orthologs having a nucleotide identity of 95% or greater. Interestingly, several procyclin-associated genes (PAGs) were disrupted or not found in this T. evansi strain, suggesting a selective loss of function in the absence of the insect life-cycle stage. Surprisingly, orthologous sequences were found in T. evansi for all 978 nuclear CDS predicted to represent the mitochondrial proteome in T. brucei, although a small number of these may have lost functionality. Consistent with previous results, the F1FO-ATP synthase γ subunit was found to have an A281 deletion, which is involved in generation of a mitochondrial membrane potential in the absence of kDNA. Candidates for CDS that are absent from the reference genome were identified in supplementary de novo assemblies of T. evansi reads. Phylogenetic analyses show that the sequenced strain belongs to a dominant group of clonal T. evansi strains with worldwide distribution that also includes isolates classified as T. equiperdum. At least three other types of T. evansi or T. equiperdum have emerged independently. Overall, the elucidation of the T. evansi genome sequence reveals extensive similarity of T. brucei and supports the contention that T. evansi should be classified as a subspecies of T. brucei.

Original languageEnglish
Article numbere3404
Number of pages22
JournalPLoS Neglected Tropical Diseases
Volume9
Issue number1
DOIs
Publication statusPublished - 8 Jan 2015

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