Open Access Open Badges Research article

Global analysis of gene expression in response to L-Cysteine deprivation in the anaerobic protozoan parasite Entamoeba histolytica

Afzal Husain12, Ghulam Jeelani13, Dan Sato4 and Tomoyoshi Nozaki15*

Author Affiliations

1 Department of Parasitology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku, Tokyo 162-8640, Japan

2 Department of Parasitology, Graduate School of Medicine, Gunma University, Maebashi 371-8511, Japan

3 Department of Biochemistry and Integrative Medical Biology, School of Medicine, Keio University, Shinjuku, Tokyo 160-8582, Japan

4 Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata 997-0052, Japan

5 Graduate School of Life and Environmental Sciences, University of Tsukuba,1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan

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BMC Genomics 2011, 12:275  doi:10.1186/1471-2164-12-275

Published: 31 May 2011



Entamoeba histolytica, an enteric protozoan parasite, causes amebic colitis and extra intestinal abscesses in millions of inhabitants of endemic areas. E. histolytica completely lacks glutathione metabolism but possesses L-cysteine as the principle low molecular weight thiol. L-Cysteine is essential for the structure, stability, and various protein functions, including catalysis, electron transfer, redox regulation, nitrogen fixation, and sensing for regulatory processes. Recently, we demonstrated that in E. histolytica, L-cysteine regulates various metabolic pathways including energy, amino acid, and phospholipid metabolism.


In this study, employing custom-made Affymetrix microarrays, we performed time course (3, 6, 12, 24, and 48 h) gene expression analysis upon L-cysteine deprivation. We identified that out of 9,327 genes represented on the array, 290 genes encoding proteins with functions in metabolism, signalling, DNA/RNA regulation, electron transport, stress response, membrane transport, vesicular trafficking/secretion, and cytoskeleton were differentially expressed (≥3 fold) at one or more time points upon L-cysteine deprivation. Approximately 60% of these modulated genes encoded proteins of no known function and annotated as hypothetical proteins. We also attempted further functional analysis of some of the most highly modulated genes by L-cysteine depletion.


To our surprise, L-cysteine depletion caused only limited changes in the expression of genes involved in sulfur-containing amino acid metabolism and oxidative stress defense. In contrast, we observed significant changes in the expression of several genes encoding iron sulfur flavoproteins, a major facilitator super-family transporter, regulator of nonsense transcripts, NADPH-dependent oxido-reductase, short chain dehydrogenase, acetyltransferases, and various other genes involved in diverse cellular functions. This study represents the first genome-wide analysis of transcriptional changes induced by L-cysteine deprivation in protozoan parasites, and in eukaryotic organisms where L-cysteine represents the major intracellular thiol.