'Transient' genetic suppression facilitates generation of hexose transporter null mutants in Leishmania mexicana. Issue 2 (10th December 2012)

• Record Type: Journal Article
• Authors: Feng, Xiuhong; Rodriguez‐Contreras, Dayana; Polley, Tamsen; Lye, Lon‐Fye; Scott, David; Burchmore, Richard J.S.; Beverley, Stephen M.; Landfear, Scott M.
• Is Part Of: Molecular microbiology. Volume 87:Issue 2(2013)
• Page Start: 412
• Page End: 429
• Publication Date: 2012-12-10
• Subjects: Molecular microbiology -- Periodicals; 572.829
• DOI: 10.1111/mmi.12106
• Languages: English
• ISSNs: 0950-382X

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>The genome of <italic>Leishmania mexicana</italic> encompasses a cluster of three glucose transporter genes designated <italic>LmxGT1</italic>, <italic>LmxGT2</italic> and <italic>LmxGT3</italic>. Functional and genetic studies of a cluster null mutant (Δ<italic>lmxgt1‐3</italic>) have dissected the roles of these proteins in <italic>Leishmania</italic> metabolism and virulence. However, null mutants were recovered at very low frequency, and comparative genome hybridizations revealed that Δ<italic>lmxgt1‐3</italic> mutants contained a linear extrachromosomal 40 kb amplification of a region on chromosome 29 not amplified in wild type parasites. These data suggested a model where this 29‐40k amplicon encoded a second site suppressor contributing to parasite survival in the absence of <italic>GT1‐3</italic> function. To test this, we quantified the frequency of recovery of knockouts in the presence of individual overexpressed open reading frames covering the 29‐40k amplicon. The data mapped the suppressor activity to <italic>PIFTC3</italic>, encoding a component of the intraflagellar transport pathway. We discuss possible models by which <italic>PIFTC3</italic> might act to facilitate loss of <italic>GT</italic>s specifically. Surprisingly, by plasmid segregation we showed that continued <italic>PIFTC3</italic> overexpression was not required for Δ<italic>lmxgt1‐3</italic> viability. These studies provide the first evidence that genetic suppression can occur by providing critical biological functions transiently. This novel form of genetic suppression may extend to other genes, pathways and organisms.</p> </abstract>