Apicomplexa rhomboids have a potential role in microneme protein cleavage during host cell invasion

Department of Biological Sciences, Imperial College London, Alexander Fleming Building, South Kensington Campus, London SW7 2AZ, UK.
International Journal for Parasitology (Impact Factor: 3.87). 07/2005; 35(7):747-56. DOI: 10.1016/j.ijpara.2005.04.001
Source: PubMed


Apicomplexan parasites secrete transmembrane (TM) adhesive proteins as part of the process leading to host cell attachment and invasion. These microneme proteins are cleaved in their TM domains by an unidentified protease termed microneme protein protease 1 (MPP1). The cleavage site sequence (IA downward arrowGG), mapped in the Toxoplasma gondii microneme proteins TgMIC2 and TgMIC6, is conserved in microneme proteins of other apicomplexans including Plasmodium species. We report here the characterisation of novel T. gondii proteins belonging to the rhomboid family of intramembrane-cleaving serine proteases. T. gondii possesses six genes encoding rhomboid-like proteins. Four are localised along the secretory pathway and therefore constitute possible candidates for MPP1 activity. Toxoplasma rhomboids TgROM1, TgROM2 and TgROM5 cleave the TM domain of Drosophila Spitz, an established substrate for rhomboids from several species, demonstrating that they are active proteases. In addition, TgROM2 cleaves chimeric proteins that contain the TM domains of TgMIC2 and TgMIC12.

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Available from: Dominique Soldati, Dec 16, 2015
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    • "The plasmid pTub8-mycROM5-DHFR was generated by subcloning via KpnI(PacI the Tub8mycROM5 fragment from pTub8mycROM5-HXGPRT plasmid (Dowse et al., 2005) into pMLC5-DHFR plasmid. "
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    ABSTRACT: Host cell entry by the Apicomplexa is associated with the sequential secretion of invasion factors from specialized apical organelles. Secretion of micronemal proteins (MICs) complexes by Toxoplasma gondii facilitates parasite gliding motility, host cell attachment and entry, as well as egress from infected cells. The shedding of MICs during these steps is mediated by micronemal protein proteases MPP1, MPP2, and MPP3. The constitutive activity of MPP1 leads to the cleavage of transmembrane MICs and is linked to the surface rhomboid protease 4 (ROM4) and possibly to rhomboid protease 5 (ROM5). To determine their importance and respective contribution to MPP1 activity, in this study ROM4 and ROM5 genes were abrogated using Cre-recombinase and CRISPR-Cas9 nuclease, respectively, and shown to be dispensable for parasite survival. Parasites lacking ROM4 predominantly engage in twirling motility and exhibit enhanced attachment and impaired invasion, whereas intracellular growth and egress are not affected. The substrates MIC2 and MIC6 are not cleaved and accumulate on the rom4-ko parasite surface. In contrast, intramembrane cleavage of AMA1 is reduced but not completely abolished. Shedding of MICs and invasion are not altered in the absence of ROM5 however this protease responsible for the residual cleavage of AMA1, is able to cleave other AMA family members and exhibits a detectable contribution to invasion in the absence of ROM4. This article is protected by copyright. All rights reserved.
    Full-text · Article · Apr 2015 · Molecular Microbiology
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    • "In the bacterium Providencia stuartii, the rhomboid homolog AarA is essential for the production of a quorum sensing signal (Stevenson et al., 2007). In eukaryotic parasites Plasmodium falciparum and Toxoplasma gondii, rhomboid proteases help to process adhesins, which are involved in invasion into host cells (Dowse et al., 2005; Buguliskis et al., 2010). However, knowledge about the functions of the largest group of rhomboid proteins, the plant rhomboids, is rather limited. "
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    ABSTRACT: Rhomboid proteins are intramembrane serine proteases that are involved in a plethora of biological functions, but the evolutionary history of the rhomboid gene family is not clear.We performed a comprehensive molecular evolutionary analysis of the rhomboid gene family and also investigated the organization and sequence features of plant rhomboids in different subfamilies.Our results showed that eukaryotic rhomboids could be divided into five subfamilies (RhoA–RhoD and PARL). Most orthology groups appeared to be conserved only as single or low-copy genes in all lineages in RhoB–RhoD and PARL, whereas RhoA genes underwent several duplication events, resulting in multiple gene copies. These duplication events were due to whole genome duplications in plants and animals and the duplicates might have experienced functional divergence. We also identified a novel group of plant rhomboid (RhoB1) that might have lost their enzymatic activity; their existence suggests that they might have evolved new mechanisms.Plant and animal rhomboids have similar evolutionary patterns. In addition, there are mutations affecting key active sites in RBL8, RBL9 and one of the Brassicaceae PARL duplicates. This study delineates a possible evolutionary scheme for intramembrane proteins and illustrates distinct fates and a mechanism of evolution of gene duplicates.
    Full-text · Article · Nov 2014 · New Phytologist
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    • "As active proteases, TgROM1, TgROM2 and TgROM5 cleaved the TM domain of Drosophila Spitz. TgROM2 cleaved chimeric proteins that contain the TM domains of TgMIC2 and TgMIC12 (Dowse et al., 2005). TgROM4 participated in processing of surface adhesins including TgMIC2, AMA1, and TgMIC3. "
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    ABSTRACT: Invasion in several apicomplexan parasites, including Eimeria tenella, is accompanied by shedding of surface adhesins by intramembrane proteolysis mediated by rhomboid protease. We have previously identified E. tenella rhomboid 3 (EtROM3), but its precise role has not been elucidated. In this study, the interactions between EtROM3 and microneme (MIC) proteins were analyzed using the yeast two hybrid technique. The results showed that c-Myc-ROM3 fusion protein interacted with EtMIC4 protein in co-transformed AH109 yeasts, which was further confirmed by immunoprecipitation assay. Smaller EtMIC4 band from co-transformed cells suggested that EtROM3 was an active protease and involved in the cleavage of EtMIC4.
    Preview · Article · Jan 2014 · Veterinary Parasitology
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