Glycoprotein Biosynthesis in a Eukaryote Lacking the Membrane Protein Rft1

Jelk, Jennifer; Gao, Ningguo; Serricchio, Mauro; Signorell, Aita; Schmidt, Roman; Bangs, James D.; Acosta-Serrano, Álvaro; Lehrman, Mark A.; Bütikofer, Peter; Menon, Anant K.

doi:10.1074/jbc.m113.479642

Cited by 31 publications

(34 citation statements)

References 37 publications

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“…It also had a slightly longer population doubling time than its parent (ϳ15 h versus ϳ12 h in liquid culture) and binding of the lectin concanavalin A (ConA) was reduced by 75%, but no other defects were apparent. An addback mutant expressing an ectopic copy of Rft1 showed wild-type levels of ConA binding, confirming that the phenotype was linked to the presence or absence of the gene (19). N-linked glycosylation is known to play a pivotal role in in the folding, quality control, stability, and function of surface and secreted proteins (21,22).…”

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confidence: 73%

“…The protein is essential in yeast; in humans, mutations have been linked to congenital disease and glycosylation defects (20). Recently, an Rft1 knockout was generated in procyclic forms of T. brucei (19). The null mutant accumulated M5-DLO but had normal levels of mature dolichol-linked oligosaccharide and was capable of glycosylating proteins.…”

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confidence: 99%

“…Rft1 is an endoplasmic reticular protein involved in the conversion of Man 5 GlcNAc 2 -PP-dolichol (M5-DLO) to M9-DLO, the precursor for N-linked glycans (17)(18)(19). The protein is essential in yeast; in humans, mutations have been linked to congenital disease and glycosylation defects (20).…”

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confidence: 99%

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A Glycosylation Mutant of Trypanosoma brucei Links Social Motility Defects In Vitro to Impaired Colonization of Tsetse Flies In Vivo

Imhof

Bütikofer

et al. 2015

Eukaryot Cell

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Transmission of African trypanosomes by tsetse flies requires that the parasites migrate out of the midgut lumen and colonize the ectoperitrophic space. Early procyclic culture forms correspond to trypanosomes in the lumen; on agarose plates they exhibit social motility, migrating en masse as radial projections from an inoculation site. We show that an Rft1 ؊/؊ mutant needs to reach a greater threshold number before migration begins, and that it forms fewer projections than its wild-type parent. The mutant is also up to 4 times less efficient at establishing midgut infections. Ectopic expression of Rft1 rescues social motility defects and restores the ability to colonize the fly. These results are consistent with social motility reflecting movement to the ectoperitrophic space, implicate N-glycans in the signaling cascades for migration in vivo and in vitro, and provide the first evidence that parasite-parasite interactions determine the success of transmission by the insect host.T setse flies (Glossina spp.) are the definitive hosts of the unicellular parasite Trypanosoma brucei, while a variety of mammals can serve as intermediate hosts. Different subspecies of T. brucei cause sleeping sickness in humans and Nagana in domestic animals. The passage of T. brucei through the tsetse fly was memorably described as a "journey fraught with hazards" (1), because the majority of parasites are either eradicated or fail to complete the life cycle. When trypanosomes are ingested by a tsetse fly as part of a blood meal, bloodstream forms differentiate into early procyclic forms in the midgut lumen. In the first few days of tsetse infection, there are two possible outcomes: the parasites are either purged by the fly or they migrate through/around the peritrophic matrix and colonize the ectoperitrophic space. Extraordinarily little is known about this process: teneral (newly hatched) flies are more susceptible to infection, most probably because the peritrophic membrane is not fully formed and it is easier for parasites to gain access to the ectoperitrophic space (2). There is evidence that several hundred parasites from the initial infectious blood meal are founders of the population in the ectoperitrophic space (3). It is not known, however, if these cross the peritrophic matrix individually or if they migrate in groups. The majority of infections in tsetse do not proceed beyond the midgut stage. Completion of the life cycle involves migration of a small number of parasites to the salivary glands, expansion of the founder population as epimastigote forms, and the production of metacyclic forms that can be transmitted to a new mammalian host (1, 3-5).The different life cycle stages of T. brucei in the fly express characteristic glycosylphosphatidylinositol (GPI)-anchored glycoproteins that are present in several million copies per cell and cover the entire surface. The early procyclic forms, which are detected in the fly midgut for up to 7 days following fly infection (6), are characterized by the presence of the GPI-anchor...

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confidence: 73%

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confidence: 99%

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A Glycosylation Mutant of Trypanosoma brucei Links Social Motility Defects In Vitro to Impaired Colonization of Tsetse Flies In Vivo

Imhof

Bütikofer

et al. 2015

Eukaryot Cell

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“…Rft1 plays a role in N-linked glycosylation and a null mutant shows reduced binding by the lectin Concanavalin A, indicating a paucity of mannose residues [29]. This mutant also shows two phenotypes in SoMo -it forms fewer radial projections than its wildtype parent and needs to reach a higher threshold before migration initiates [28].…”

Section: Somo Is Restricted To Early Procyclic Forms and Correlates Wmentioning

confidence: 99%

The Social Life of African Trypanosomes

Imhof

Roditi

2015

Trends in Parasitology

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The unicellular parasite Trypanosoma brucei shuttles between its definitive host, the tsetse fly, and various mammals including humans. In the fly T. brucei must first migrate to the ectoperitrophic space, establish a persistent infection of the midgut and then migrate to the salivary glands before being transmitted to a new mammalian host. In 2010 it was shown that insect stages of the parasite (procyclic forms) exhibit social motility (SoMo) when cultured on a semi-solid surface, and it was postulated that this behaviour might reflect a migration step in the tsetse fly. Now, almost five years after the initial report, several new publications shed some light on the biological function of SoMo and provide insights into the underlying signaling pathways.

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“…In subsequent reactions, five GTP-activated mannoses are added in a stepwise manner via three specific GTs to build the branched heptasaccharide. In the second part of the bipartite assembly process, M5-DLO is "flipped" across the membrane to face the ER lumen in an ATP-independent manner, although the identification of the flippase remains a source of controversy (34)(35)(36)(37). Once oriented to face the ER lumen, the flipped lipid-linked heptasaccharide is further elongated by four mannose and three glucose residues, each donated from DolP-mannose or -glucose; charged on the cytoplasmic face of the ER membrane; and translocated to face the ER lumen by unidentified flippases (38).…”

Section: Eukaryal Protein N-glycosylationmentioning

confidence: 99%

N-Linked Glycosylation in Archaea: a Structural, Functional, and Genetic Analysis

Jarrell

Ding

Meyer

et al. 2014

Microbiol Mol Biol Rev

180

214

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SUMMARY N-glycosylation of proteins is one of the most prevalent posttranslational modifications in nature. Accordingly, a pathway with shared commonalities is found in all three domains of life. While excellent model systems have been developed for studying N-glycosylation in both Eukarya and Bacteria , an understanding of this process in Archaea was hampered until recently by a lack of effective molecular tools. However, within the last decade, impressive advances in the study of the archaeal version of this important pathway have been made for halophiles, methanogens, and thermoacidophiles, combining glycan structural information obtained by mass spectrometry with bioinformatic, genetic, biochemical, and enzymatic data. These studies reveal both features shared with the eukaryal and bacterial domains and novel archaeon-specific aspects. Unique features of N-glycosylation in Archaea include the presence of unusual dolichol lipid carriers, the use of a variety of linking sugars that connect the glycan to proteins, the presence of novel sugars as glycan constituents, the presence of two very different N-linked glycans attached to the same protein, and the ability to vary the N-glycan composition under different growth conditions. These advances are the focus of this review, with an emphasis on N-glycosylation pathways in Haloferax , Methanococcus , and Sulfolobus .

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Glycoprotein Biosynthesis in a Eukaryote Lacking the Membrane Protein Rft1

Cited by 31 publications

References 37 publications

A Glycosylation Mutant of Trypanosoma brucei Links Social Motility Defects In Vitro to Impaired Colonization of Tsetse Flies In Vivo

A Glycosylation Mutant of Trypanosoma brucei Links Social Motility Defects In Vitro to Impaired Colonization of Tsetse Flies In Vivo

The Social Life of African Trypanosomes

N-Linked Glycosylation in Archaea: a Structural, Functional, and Genetic Analysis

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