Integration of a small integral membrane protein, M2, of influenza virus into the endoplasmic reticulum: analysis of the internal signal-anchor domain of a protein with an ectoplasmic NH2 terminus.

Hull, J D; Gilmore, Reid; Lamb, Robert A.

doi:10.1083/jcb.106.5.1489

Cited by 72 publications

(49 citation statements)

References 64 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Given the topology of PfSBP1 within the Maurer's clefts, with its N-terminal domain facing the lumen of the cleft and its C-terminal domain residing within the erythrocyte cytoplasm (14), PfSBP1 seems to best resemble a type Ib protein (although this classification was initially developed to describe the orientation of integral membrane proteins in the plasma membrane of model eukaryotes and not in membrane systems outside the cell boundaries, such as the PVM and the Maurer's clefts) (39). As shown in other systems, deleting a few amino acids from the transmembrane domain of a type Ib secreted protein abolishes insertion of the nascent protein into the ER (40). Similarly, deleting six amino acids from the transmembrane domain of PfSBP1, within the context of full-length PfSBP1, resulted in an export-deficient phenotype, with the protein remaining within the parasite's cytoplasm ( Figure 6A).…”

Section: Discussionmentioning

confidence: 99%

Export of PfSBP1 to the Plasmodium falciparum Maurer’s Clefts

Saridaki

Fröhlich

Braun-Breton

et al. 2009

Traffic

View full text Add to dashboard Cite

The human malaria parasite Plasmodium falciparum exports determinants of virulence and pathology to destinations within the host erythrocyte, including the erythrocyte cytoplasm, plasma membrane and membrane profiles of parasite origin termed Maurer's clefts. Most of the exported proteins contain a conserved pentameric motif termed plasmodial export element (PEXEL)/vacuolar transfer signal (VTS) that functions as a cleavable sorting signal permitting export to the host erythrocyte. However, there are some exported proteins, such as the skeleton-binding protein 1 (PfSBP1) that lack the PEXEL/VTS motif and that are not N-terminally processed, suggesting the presence of alternative sorting signals and/or mechanisms. In this study, we have investigated trafficking of PfSBP1 to the Maurer's clefts. Our data show that the transmembrane domain of PfSBP1 functions as an internal signal sequence for entry into the parasite's secretory pathway and for transport to the parasite plasma membrane. Trafficking beyond the parasite's plasma membrane required additional N-terminal domains, which are characterized by a high negative net charge. Biochemical data indicate that these domains affect the solubility and extraction profile, the orientation of the protein within the membrane and the subcellular localization. Our findings suggest new principles of protein export in P. falciparum-infected erythrocytes.

show abstract

Section: Discussionmentioning

confidence: 99%

Export of PfSBP1 to the Plasmodium falciparum Maurer’s Clefts

Saridaki

Fröhlich

Braun-Breton

et al. 2009

Traffic

View full text Add to dashboard Cite

show abstract

“…NF-Ela and GF-1 subclones were linearized with NdeI and transcribed by using T3 RNA polymerase; NF-Elb and NF-Elc subclones were linearized with HindIII and transcribed with SP6 RNA polymerase. Five micrograms of linearized template was transcribed after the method of Hull et al (1988), in which a cap analog [mTG(5')ppp(5')G; Pharmacia] was included to subsequently favor efficient translation. An aliquot of RNA from the reactions was denatured and electrophoresed on a 1.5% agarose gel containing 2.2 M formaldehyde and then stained with ethidium bromide.…”

Section: In Vitro Expression Of Nf-e1 Cdna Clonesmentioning

confidence: 99%

Activity and tissue-specific expression of the transcription factor NF-E1 multigene family.

Yamamoto¹,

Ko²,

Leonard³

et al. 1990

Genes Dev.

602

508

View full text Add to dashboard Cite

NF-E1, a DNA-binding protein that recognizes the general consensus motif WGATAR, is the first tissue-specific factor to be identified in erythroid cells. Using a probe from the murine GF-1 (NF-E1) cDNA clone, we isolated three homologous chicken cDNAs: One of these corresponds to an mRNA (NF-Ela) that is abundantly and exclusively expressed in erythroid cells; a second mRNA (NF-Elb) is also expressed in all developmental stages of erythroid cells but is additionally found in a limited subset of other chicken tissues; mRNA representative of a third gene (NF-Elc) is expressed only in definitive (adult) erythrocytes within the red cell lineage but is also abundantly expressed in T lymphocytes and brain. All NF-E1 proteins are highly conserved within the DNA-binding domain and bind to the consensus motif with similar affinities in vitro; they are also all stimulatory trans-acting factors in vivo. The factors differ quantitatively in their ability to trans-activate reporter genes in which the number and position of cognate binding sites is varied relative to the transcriptional initiation site. These data suggest that the NF-E1 consensus motif directs a broader and more complicated array of developmental transcriptional regulatory processes than has been assumed and that NF-Elc may play a unique regulatory role in the developing chicken brain and in T lymphocytes.

show abstract

“…This postulated splaying open of the helices in the open state is consistent with the increased accessibility of the internal residues to organic reagents that occurs when the Shaker family channels are activated (52,59). The influenza virus M 2 protein is a model of minimalism because it has only a single multifunctional TM domain, which contains the pore of the channel (25), acts both to target the protein initially to the membrane of the rough endoplasmic reticulum (ER) and anchor the protein in the ER membrane (61), and, as we show here, contains the activation gate.…”

mentioning

confidence: 99%

The Gate of the Influenza Virus M2 Proton Channel Is Formed by a Single Tryptophan Residue

Tang¹,

Zaitseva²,

Lamb

et al. 2002

Journal of Biological Chemistry

231

319

View full text Add to dashboard Cite

The influenza virus M 2 proton-selective ion channel is known to be essential for acidifying the interior of virions during virus uncoating in the lumen of endosomes. The M 2 protein is a homotetramer that contains four 19-residue transmembrane (TM) domains. These TM domains are multifunctional, because they contain the channel pore and also anchor the protein in membranes. The M 2 protein is gated by pH, and thus we have measured pH-gated currents, the accessibility of the pore to Cu 2؉ , and the effect of a protein-modifying reagent for a series of TM domain mutant M 2 proteins. The results indicate that gating of the M 2 ion channel is governed by a single side chain at residue 41 of the TM domain and that this property is mediated by an indole moiety. Unlike many ion channels where the gate is formed by a whole segment of a protein, our data suggest a model of striking simplicity for the M 2 ion channel protein, with the side chain of Trp 41 blocking the pore of the M 2 channel when pH out is high and with this side chain leaving the pore when pH out is low. Thus, the Trp 41 side chain acts as the gate that opens and closes the pore.The prediction that the influenza A virus M 2 protein has a proton-selective ion channel activity (Refs. 1 and 2 and reviewed in Ref.3) arose from a coupling of various observations on the life cycle of influenza virus. The M 2 protein is an integral membrane protein that is expressed at the plasma membrane of influenza virus-infected cells and is incorporated in small amounts into budding virions (4, 5). Studies on the mechanism of action of the anti-viral drug, amantadine (1-aminoadamantine hydrochloride), indicated that viral escape mutants resistant to the drug mapped to the transmembrane (TM) 1 domain of the M 2 protein (6) and that amantadine affected two steps in the life cycle, virus uncoating and virus maturation. The effect of amantadine on inhibition of uncoating is general to all strains of influenza A virus (7, 8) (reviewed in Refs. 3, 9 -11). When a virion has entered the cell by receptor-mediated endocytosis and the virus particle is in the acidic environment of the endosomal lumen, the M 2 ion channel is activated and conducts protons across the viral membrane. The lowered internal virion pH is thought to weaken protein-protein interactions between the viral matrix protein (M1) and the ribonucleoprotein (RNP) core (7,(12)(13)(14)(15)). In the presence of amantadine, influenza virus uncoating is incomplete, because the M1 protein is not released from the RNPs and the RNPs fail to enter the nucleus. Normally, influenza virus RNPs are transcribed and replicated in the nucleus (reviewed in Ref. 10). For some influenza virus subtypes, amantadine inhibits a "late" step in virus replication. The M 2 ion channel activity is activated during transport of the M 2 protein through the exocytic pathway; this ion channel activity raises the lumenal pH of the trans Golgi network (TGN), equilibrating pH with that of the cytoplasm (1, 17-22). Thus, the intralumenal pH of the TGN i...

show abstract

Integration of a small integral membrane protein, M2, of influenza virus into the endoplasmic reticulum: analysis of the internal signal-anchor domain of a protein with an ectoplasmic NH2 terminus.

Cited by 72 publications

References 64 publications

Export of PfSBP1 to the Plasmodium falciparum Maurer’s Clefts

Export of PfSBP1 to the Plasmodium falciparum Maurer’s Clefts

Activity and tissue-specific expression of the transcription factor NF-E1 multigene family.

The Gate of the Influenza Virus M2 Proton Channel Is Formed by a Single Tryptophan Residue

Contact Info

Product

Resources

About