scholarly journals Single point mutation in tick-borne encephalitis virus prM protein induces a reduction of virus particle secretion

2004 ◽  
Vol 85 (10) ◽  
pp. 3049-3058 ◽  
Author(s):  
Kentarou Yoshii ◽  
Akihiro Konno ◽  
Akiko Goto ◽  
Junko Nio ◽  
Mayumi Obara ◽  
...  
Keyword(s):  
Point Mutation ◽  
Single Point ◽  
Expression System ◽  
Envelope Proteins ◽  
Viral Envelope ◽  
Single Point Mutation ◽  
Virus Envelope ◽  
Electron Microscopic ◽  
Transport Pathway ◽  
Tick Borne Encephalitis

Flaviviruses are assembled to bud into the lumen of the endoplasmic reticulum (ER) and are secreted through the vesicle transport pathway. Virus envelope proteins play important roles in this process. In this study, the effect of mutations in the envelope proteins of tick-borne encephalitis (TBE) virus on secretion of virus-like particles (VLPs), using a recombinant plasmid expression system was analysed. It was found that a single point mutation at position 63 in prM induces a reduction in secretion of VLPs. The mutation in prM did not affect the folding of the envelope proteins, and chaperone-like activity of prM was maintained. As observed by immunofluorescence microscopy, viral envelope proteins with the mutation in prM were scarce in the Golgi complex, and accumulated in the ER. Electron microscopic analysis of cells expressing the mutated prM revealed that many tubular structures were present in the lumen. The insertion of the prM mutation at aa 63 into the viral genome reduced the production of infectious virus particles. This data suggest that prM plays a crucial role in the virus budding process.

scholarly journals Folding and Dimerization of Tick-Borne Encephalitis Virus Envelope Proteins prM and E in the Endoplasmic Reticulum

2002 ◽  
Vol 76 (11) ◽  
pp. 5480-5491 ◽  
Author(s):  
Ivo C. Lorenz ◽  
Steven L. Allison ◽  
Franz X. Heinz ◽  
Ari Helenius
Keyword(s):  
Disulfide Bonds ◽  
Signal Sequence ◽  
Expression System ◽  
Conformational Epitope ◽  
Envelope Proteins ◽  
Viral Glycoprotein ◽  
Virus Envelope ◽  
Folded Structure ◽  
Tick Borne Encephalitis ◽  
Tbe Virus

ABSTRACT Flavivirus envelope proteins are synthesized as part of large polyproteins that are co- and posttranslationally cleaved into their individual chains. To investigate whether the interaction of neighboring proteins within the precursor protein is required to ensure proper maturation of the individual components, we have analyzed the folding of the flavivirus tick-borne encephalitis (TBE) virus envelope glycoproteins prM and E by using a recombinant plasmid expression system and virus-infected cells. When expressed in their polyprotein context, prM and E achieved their native folded structures with half-times of approximately 4 min for prM and about 15 min for E. They formed heterodimeric complexes within a few minutes after synthesis that were required for the final folding of E but not for that of prM. Heterodimers could also be formed in trans when these proteins were coexpressed from separate constructs. When expressed without prM, E could form disulfide bonds but did not express a specific conformational epitope and remained sensitive to reduction by dithiothreitol. This is consistent with a chaperone-like role for prM in the folding of E. PrM was able to achieve its native folded structure without coexpression of E, but signal sequence cleavage at the N terminus was delayed. Our results show that prM is an especially rapidly folding viral glycoprotein, that polyprotein cleavage and folding of the TBE virus envelope proteins occurs in a coordinated sequence of processing steps, and that proper and efficient maturation of prM and E can only be achieved by cosynthesis of these two proteins.

scholarly journals A single point mutation converts a proton-pumping rhodopsin into a red-shifted, turn-on fluorescent sensor for chloride

2021 ◽  
Author(s):  
Jasmine N. Tutol ◽  
Jessica Lee ◽  
Hsichuan Chi ◽  
Farah N. Faizuddin ◽  
Sameera S. Abeyrathna ◽  
...  
Keyword(s):  
Point Mutation ◽  
Fluorescent Sensor ◽  
Single Point ◽  
Proton Pumping ◽  
Single Point Mutation ◽  
Turn On ◽  
Gloeobacter Violaceus

By utilizing laboratory-guided evolution, we have converted the fluorescent proton-pumping rhodopsin GR from Gloeobacter violaceus into GR1, a red-shifted, turn-on fluorescent sensor for chloride.

scholarly journals Structural basis for a complex I mutation that blocks pathological ROS production

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Zhan Yin ◽  
Nils Burger ◽  
Duvaraka Kula-Alwar ◽  
Dunja Aksentijević ◽  
Hannah R. Bridges ◽  
...  
Keyword(s):  
Point Mutation ◽  
Complex I ◽  
Structural Changes ◽  
Ischemia Reperfusion ◽  
Single Point ◽  
Structural Basis ◽  
Single Point Mutation ◽  
Ros Production

AbstractMitochondrial complex I is central to the pathological reactive oxygen species (ROS) production that underlies cardiac ischemia–reperfusion (IR) injury. ND6-P25L mice are homoplasmic for a disease-causing mtDNA point mutation encoding the P25L substitution in the ND6 subunit of complex I. The cryo-EM structure of ND6-P25L complex I revealed subtle structural changes that facilitate rapid conversion to the “deactive” state, usually formed only after prolonged inactivity. Despite its tendency to adopt the “deactive” state, the mutant complex is fully active for NADH oxidation, but cannot generate ROS by reverse electron transfer (RET). ND6-P25L mitochondria function normally, except for their lack of RET ROS production, and ND6-P25L mice are protected against cardiac IR injury in vivo. Thus, this single point mutation in complex I, which does not affect oxidative phosphorylation but renders the complex unable to catalyse RET, demonstrates the pathological role of ROS production by RET during IR injury.

Scarcity of λ1 B cells in mice with a single point mutation in Cλ1 is due to a low BCR signal caused by misfolded lambda1 light chain

2007 ◽  
Vol 44 (6) ◽  
pp. 1417-1428 ◽  
Author(s):  
Veronica V. Volgina ◽  
Tianhe Sun ◽  
Grazyna Bozek ◽  
Terence E. Martin ◽  
Ursula Storb
Keyword(s):  
B Cells ◽  
Point Mutation ◽  
Light Chain ◽  
Single Point ◽  
Single Point Mutation

Shifting Substrate Specificity of Human Glutathione Transferase (from Class Pi to Class Alpha) by a Single Point Mutation

1998 ◽  
Vol 252 (1) ◽  
pp. 184-189 ◽  
Author(s):  
Marzia Nuccetelli ◽  
Anna P. Mazzetti ◽  
Jamie Rossjohn ◽  
Michael W. Parker ◽  
Philip Board ◽  
...  
Keyword(s):  
Substrate Specificity ◽  
Point Mutation ◽  
Glutathione Transferase ◽  
Single Point ◽  
Single Point Mutation
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