HDL and the Amphipathic Helix

2015 ◽  
pp. 1-13
Author(s):  
Jere P. Segrest
Keyword(s):  
Amphipathic Helix

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 Quantitative Molecular Modeling of Membrane Curvature Induction by an Amphipathic Helix

2014 ◽  
Vol 106 (2) ◽  
pp. 505a
Author(s):  
Alexander J. Sodt ◽  
Richard W. Pastor
Keyword(s):  
Molecular Modeling ◽  
Membrane Curvature ◽  
Amphipathic Helix

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

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 An amphipathic helix enables septins to sense micrometer-scale membrane curvature

2019 ◽  
Vol 218 (4) ◽  
pp. 1128-1137 ◽  
Author(s):  
Kevin S. Cannon ◽  
Benjamin L. Woods ◽  
John M. Crutchley ◽  
Amy S. Gladfelter
Keyword(s):  
Membrane Curvature ◽  
Amphipathic Helix ◽  
Curvature Sensing ◽  
C Terminus ◽  
Number Of Binding Sites ◽  
Curved Membranes ◽  
Necessary And Sufficient ◽  
Micrometer Scale

Cell shape is well described by membrane curvature. Septins are filament-forming, GTP-binding proteins that assemble on positive, micrometer-scale curvatures. Here, we examine the molecular basis of curvature sensing by septins. We show that differences in affinity and the number of binding sites drive curvature-specific adsorption of septins. Moreover, we find septin assembly onto curved membranes is cooperative and show that geometry influences higher-order arrangement of septin filaments. Although septins must form polymers to stay associated with membranes, septin filaments do not have to span micrometers in length to sense curvature, as we find that single-septin complexes have curvature-dependent association rates. We trace this ability to an amphipathic helix (AH) located on the C-terminus of Cdc12. The AH domain is necessary and sufficient for curvature sensing both in vitro and in vivo. These data show that curvature sensing by septins operates at much smaller length scales than the micrometer curvatures being detected.

scholarly journals Essential Mycoplasma Glycolipid Synthase Adheres to the Cell Membrane by Means of an Amphipathic Helix

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Javier Romero-García ◽  
Xevi Biarnés ◽  
Antoni Planas
Keyword(s):  
Cell Membrane ◽  
Amphipathic Helix
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