scholarly journals A signal comprising a basic cluster and an amphipathic  -helix interacts with lipids and is required for the transport of Ist2 to the yeast cortical ER

2009 ◽  
Vol 122 (5) ◽  
pp. 625-635 ◽  
Author(s):  
K. Maass ◽  
M. A. Fischer ◽  
M. Seiler ◽  
K. Temmerman ◽  
W. Nickel ◽  
...  
Keyword(s):  
Amphipathic Helix ◽  
Basic Cluster

The SPI2-encoded SseA chaperone has discrete domains required for SseB stabilization and export, and binds within the C-terminus of SseB and SseD

Microbiology ◽  
2004 ◽  
Vol 150 (7) ◽  
pp. 2055-2068 ◽  
Author(s):  
Daniel V. Zurawski ◽  
Murry A. Stein
Keyword(s):  
Type Iii Secretion ◽  
Coiled Coil ◽  
Amphipathic Helix ◽  
Yeast Two Hybrid ◽  
C Terminus ◽  
N Terminus ◽  
Domain Mapping ◽  
Self Association ◽  
Discrete Domains ◽  
Two Hybrid

SseA, a key Salmonella virulence determinant, is a small, basic pI protein encoded within the Salmonella pathogenicity island 2 and serves as a type III secretion system chaperone for SseB and SseD. Both SseA partners are subunits of the surface-localized translocon module that delivers effectors into the host cell; SseB is predicted to compose the translocon sheath and SseD is a putative translocon pore subunit. In this study, SseA molecular interactions with its partners were characterized further. Yeast two-hybrid screens indicate that SseA binding requires a C-terminal domain within both partners. An additional central domain within SseD was found to influence binding. The SseA-binding region within SseB was found to encompass a predicted amphipathic helix of a type participating in coiled-coil interactions that are implicated in the assembly of translocon sheaths. Deletions that impinge upon this putative coiled-coiled domain prevent SseA binding, suggesting that SseA occupies a portion of the coiled-coil. SseA occupancy of this motif is envisioned to be sufficient to prevent premature SseB self-association inside bacteria. Domain mapping on the chaperone was also performed. A deletion of the SseA N-terminus, or site-directed mutations within this region, allowed stabilization of SseB, but its export was disrupted. Therefore, the N-terminus of SseA provides a function that is essential for SseB export, but dispensable for partner binding and stabilization.

scholarly journals Prediction of Amphipathic Helix - Membrane Interactions with Rosetta

2021 ◽  
Vol 120 (3) ◽  
pp. 19a
Author(s):  
Alican Gulsevin ◽  
Jens Meiler
Keyword(s):  
Amphipathic Helix ◽  
Membrane Interactions

scholarly journals Cell Death Triggered by a Putative Amphipathic Helix of Radish mosaic virus Helicase Protein Is Tightly Correlated With Host Membrane Modification

2015 ◽  
Vol 28 (6) ◽  
pp. 675-688 ◽  
Author(s):  
Masayoshi Hashimoto ◽  
Ken Komatsu ◽  
Ryo Iwai ◽  
Takuya Keima ◽  
Kensaku Maejima ◽  
...  
Keyword(s):  
Cell Death ◽  
Mosaic Virus ◽  
Defense Responses ◽  
Plant Viruses ◽  
Amphipathic Helix ◽  
Membrane Structures ◽  
Membrane Modification ◽  
Systemic Necrosis ◽  
Amino Terminal ◽  
Er Membrane

Systemic necrosis is one of the most severe symptoms caused by plant RNA viruses. Recently, systemic necrosis has been suggested to have similar features to a defense response referred to as the hypersensitive response (HR), a form of programmed cell death. In virus-infected plant cells, host intracellular membrane structures are changed dramatically for more efficient viral replication. However, little is known about whether this replication-associated membrane modification is the cause of the symptoms. In this study, we identified an amino-terminal amphipathic helix of the helicase encoded by Radish mosaic virus (RaMV) (genus Comovirus) as an elicitor of cell death in RaMV-infected plants. Cell death caused by the amphipathic helix had features similar to HR, such as SGT1-dependence. Mutational analyses and inhibitor assays using cerulenin demonstrated that the amphipathic helix–induced cell death was tightly correlated with dramatic alterations in endoplasmic reticulum (ER) membrane structures. Furthermore, the cell death–inducing activity of the amphipathic helix was conserved in Cowpea mosaic virus (genus Comovirus) and Tobacco ringspot virus (genus Nepovirus), both of which are classified in the family Secoviridae. Together, these results indicate that ER membrane modification associated with viral intracellular replication may be recognized to prime defense responses against plant viruses.

Reconstitution of human atlastin fusion activity reveals autoinhibition by the C terminus

2021 ◽  
Vol 221 (2) ◽  
Author(s):  
Daniel Crosby ◽  
Melissa R. Mikolaj ◽  
Sarah B. Nyenhuis ◽  
Samantha Bryce ◽  
Jenny E. Hinshaw ◽  
...  
Keyword(s):  
Network Formation ◽  
Fusion Activity ◽  
Amphipathic Helix ◽  
Alternate Splicing ◽  
Charge Reversal ◽  
Splice Isoforms ◽  
C Terminus ◽  
Splice Isoform ◽  
Inhibitory Domain ◽  
Α Helix

ER network formation depends on membrane fusion by the atlastin (ATL) GTPase. In humans, three paralogs are differentially expressed with divergent N- and C-terminal extensions, but their respective roles remain unknown. This is partly because, unlike Drosophila ATL, the fusion activity of human ATLs has not been reconstituted. Here, we report successful reconstitution of fusion activity by the human ATLs. Unexpectedly, the major splice isoforms of ATL1 and ATL2 are each autoinhibited, albeit to differing degrees. For the more strongly inhibited ATL2, autoinhibition mapped to a C-terminal α-helix is predicted to be continuous with an amphipathic helix required for fusion. Charge reversal of residues in the inhibitory domain strongly activated its fusion activity, and overexpression of this disinhibited version caused ER collapse. Neurons express an ATL2 splice isoform whose sequence differs in the inhibitory domain, and this form showed full fusion activity. These findings reveal autoinhibition and alternate splicing as regulators of atlastin-mediated ER fusion.

scholarly journals C-terminal juxtamembrane region of full-length M2 protein forms a membrane surface associated amphipathic helix

2015 ◽  
Vol 24 (3) ◽  
pp. 426-429 ◽  
Author(s):  
Shenstone Huang ◽  
Bryan Green ◽  
Megan Thompson ◽  
Richard Chen ◽  
Jessica Thomaston ◽  
...  
Keyword(s):  
Membrane Surface ◽  
Full Length ◽  
Amphipathic Helix ◽  
M2 Protein ◽  
Juxtamembrane Region

scholarly journals Inferring Companies Similarities from Brazilian Government Expenditure Data

2015 ◽  
Author(s):  
Marcelo Pita ◽  
Gustavo Torres
Keyword(s):  
Cluster Analysis ◽  
Federal Government ◽  
Government Expenditure ◽  
Connected Components ◽  
Public Agencies ◽  
Basic Cluster ◽  
Brazilian Government ◽  
Expenditure Data ◽  
Financial Transactions

A graph-based method is proposed for inferring similarities among companies from their affiliations in the context of expenditure financial transactions in the Brazilian Federal Government. There are trusted and untrusted companies. We performed a basic cluster analysis in the companies network to verify whether clusters (connected components) are discriminative concerning companies trustworthiness. Results show evidences that this is true, reinforcing the following hypotheses: (1) there are suppliers associations, which evidences the formation of cartels; and (2) public agencies and agents play an important role in the legality of financial transactions.

Missense mutation Leu72Pro located on the carboxyl terminal amphipathic helix of apolipoprotein C-II causes familial chylomicronemia syndrome

2006 ◽  
Vol 364 (1-2) ◽  
pp. 256-259 ◽  
Author(s):  
Ching-Wan Lam ◽  
Yuet-Ping Yuen ◽  
Wai-Fun Cheng ◽  
Yan-Wo Chan ◽  
Sui-Fan Tong
Keyword(s):  
Missense Mutation ◽  
Amphipathic Helix ◽  
Apolipoprotein C ◽  
Carboxyl Terminal

scholarly journals A Basic Cluster in the N Terminus of Yellow Fever Virus NS2A Contributes to Infectious Particle Production

2015 ◽  
Vol 89 (9) ◽  
pp. 4951-4965 ◽  
Author(s):  
Stephanie Voßmann ◽  
Janett Wieseler ◽  
Romy Kerber ◽  
Beate Mareike Kümmerer
Keyword(s):  
Yellow Fever ◽  
Particle Production ◽  
Yellow Fever Virus ◽  
Fever Virus ◽  
Physical Interaction ◽  
Site Mutation ◽  
Virion Assembly ◽  
Permeabilized Cells ◽  
Basic Cluster ◽  
N Terminus

ABSTRACTThe flavivirus NS2A protein is involved in the assembly of infectious particles. To further understand its role in this process, a charged-to-alanine scanning analysis was performed on NS2A encoded by an infectious cDNA clone of yellow fever virus (YFV). Fifteen mutants containing single, double, or triple charged-to-alanine changes were tested. Five of them did not produce infectious particles, whereas efficient RNA replication was detectable for two of the five NS2A mutants (R22A-K23A-R24A and R99A-E100A-R101A mutants). Prolonged cultivation of transfected cells resulted in the recovery of pseudorevertants. Besides suppressor mutants in NS2A, a compensating second-site mutation in NS3 (D343G) arose for the NS2A R22A-K23A-R24A mutant. We found this NS3 mutation previously to be suppressive for the NS2Aα cleavage site Q189S mutant, also deficient in virion assembly. In this study, the subsequently suggested interaction between NS2A and NS3 was proven by coimmunoprecipitation analyses. Using selectively permeabilized cells, we could demonstrate that the regions encompassing R22A-K23A-R24A and Q189S in NS2A are localized to the cytoplasm, where NS3 is also known to reside. However, the defect in particle production observed for the NS2A R22A-K23A-R24A and Q189S mutants was not due to a defect in physical interaction between NS2A and NS3, as the NS2A mutations did not interrupt NS3 interaction. In fact, a region just upstream of R22-K23-R24 was mapped to be critical for NS2A-NS3 interaction. Taken together, these data support a complex interplay between YFV NS2A and NS3 in virion assembly and identify a basic cluster in the NS2A N terminus to be critical in this process.IMPORTANCEDespite an available vaccine, yellow fever remains endemic in tropical areas of South America and Africa. To control the disease, antiviral drugs are required, and an understanding of the determinants of virion assembly is central to their development. In this study, we identified a basic cluster of amino acids in the N terminus of YFV NS2A which inhibited virion assembly upon mutation. The defect was rescued by a spontaneously occurring mutation in NS3. Our study proves an interaction between NS2A and NS3, which, remarkably, was maintained for the NS2A mutant in the presence and absence of the NS3 mutation. This suggests a role for other viral and/or cellular proteins in virion assembly. Residues important for YFV virion production reported here only partially coincided with those reported for other flaviviruses, suggesting that the determinants for particle production are virus specific. Reconstruction of a YFV encoding tagged NS2A paves the way to identify further NS2A interaction partners.

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