Recombinant Norwalk virus Genome polyprotein (ORF1)

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Cat. No.
BT2507784
Source
in vitro E.coli expression system
Synonyms
ORF1; Genome polyprotein
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Description

Introduction to Recombinant Norwalk Virus Genome Polyprotein (ORF1)

The Recombinant Norwalk virus Genome polyprotein encoded by Open Reading Frame 1 (ORF1) is a crucial component of the Norwalk virus, which belongs to the family Caliciviridae. This virus is a major cause of acute gastroenteritis worldwide. The ORF1 polyprotein is a large precursor protein that undergoes proteolytic cleavage to produce several non-structural proteins essential for viral replication.

Structure and Composition of ORF1 Polyprotein

The ORF1 polyprotein of the Norwalk virus is approximately 200 kDa in size and is composed of six non-structural proteins:

  • N-terminal p48 protein (NS1-2): Involved in early stages of viral replication.

  • Nucleoside triphosphatase (NTPase): Plays a role in viral RNA synthesis.

  • 3A-like p22 protein (NS4): Similar to proteins found in other viruses, potentially involved in membrane modification.

  • Viral genome-linked VPg protein (NS5): Covalently linked to the viral RNA genome.

  • 3C-like protease (NS6): Responsible for cleaving the ORF1 polyprotein.

  • RNA-dependent RNA polymerase (RdRp) (NS7): Essential for viral RNA replication .

Proteolytic Processing of ORF1 Polyprotein

The proteolytic processing of the ORF1 polyprotein is mediated by the virus-encoded cysteine proteinase. This process involves several cleavage sites, resulting in the production of mature non-structural proteins. The cleavage sites include Q330/G331, Q696/G697, E875/G876, E1008/A1009, and E1189/G1190 . Stable precursors during this process include p20VPg and ProPol, which are analogous to picornavirus proteins .

Research Findings and Implications

Studies have shown that the N-terminal protein of the ORF1 polyprotein colocalizes with the Golgi apparatus in host cells, leading to its disassembly. This interaction is crucial for viral replication and pathogenesis . The use of recombinant technology to express these proteins has facilitated detailed analysis of their functions and interactions.

Table 2: Cleavage Sites in ORF1 Polyprotein

Cleavage SitePosition
Q330/G331N-terminal/NTPase junction
Q696/G697NTPase/p20 junction
E875/G876p20/VPg junction
E1008/A1009VPg/Protease junction
E1189/G1190Protease/RdRp junction

Product Specs

Form
Lyophilized powder
Note: While we prioritize shipping the format currently in stock, please specify your format preference in order notes for customized preparation.
Lead Time
Delivery times vary depending on the purchasing method and location. Please contact your local distributor for precise delivery estimates.
Note: All proteins are shipped with standard blue ice packs unless dry ice shipping is specifically requested and pre-arranged. Additional fees apply for dry ice shipping.
Notes
Avoid repeated freeze-thaw cycles. Store working aliquots at 4°C for up to one week.
Reconstitution
Centrifuge the vial briefly before opening to collect the contents. Reconstitute the protein in sterile deionized water to a concentration of 0.1-1.0 mg/mL. We recommend adding 5-50% glycerol (final concentration) and aliquoting for long-term storage at -20°C/-80°C. Our standard glycerol concentration is 50% and can be used as a reference.
Shelf Life
Shelf life depends on several factors, including storage conditions, buffer composition, temperature, and protein stability. Generally, liquid formulations have a 6-month shelf life at -20°C/-80°C, while lyophilized formulations have a 12-month shelf life at -20°C/-80°C.
Storage Condition
Store at -20°C/-80°C upon receipt. Aliquot for multiple uses. Avoid repeated freeze-thaw cycles.
Tag Info
Tag type is determined during the manufacturing process.
The tag type is determined during production. If you require a specific tag, please inform us, and we will prioritize its development.
Synonyms
ORF1; Genome polyprotein
Buffer Before Lyophilization
Tris/PBS-based buffer, 6% Trehalose.
Datasheet
Please contact us to get it.
Expression Region
1282-1789
Protein Length
Full Length of Mature Protein
Species
Norwalk virus (strain GI/Human/United States/Norwalk/1968) (Hu/NV/NV/1968/US)
Target Names
ORF1
Target Protein Sequence
GGDKGHYAGHEIVRYGSGPALSTKTKFWRSSPEPLPPGVYEPAYLGGKDPRVQNGPSLQQ VLRDQLKPFADPRGRMPEPGLLEAAVETVTSMLEQTMDTPSPWSYADACQSLDKTTSSGY PHHKRKNDDWNGTTFVGELGEQAAHANNMYENAKHMKPIYTAALKDELVKPEKIYQKVKK RLLWGADLGTVVRAARAFGPFCDAIKSHVIKLPIKVGMNTIEDGPLIYAEHAKYKNHFDA DYTAWDSTQNRQIMTESFSIMSRLTASPELAEVVAQDLLAPSEMDVGDYVIRVKEGLPSG FPCTSQVNSINHWIITLCALSEATGLSPDVVQSMSYFSFYGDDEIVSTDIDFDPARLTQI LKEYGLKPTRPDKTEGPIQVRKNVDGLVFLRRTISRDAAGFQGRLDRASIERQIFWTRGP NHSDPSETLVPHTQRKIQLISLLGEASLHGEKFYRKISSKVIHEIKTGGLEMYVPGWQAM FRWMRFHDLGLWTGDRDLLPEFVNDDGV
Uniprot No.
Q83883

Target Background

Function
Protein p48 may contribute to viral replication through interaction with the host protein VAPA (vesicle-associated membrane protein A), which is involved in SNARE-mediated vesicle fusion. This interaction may target the replication complex to intracellular membranes. The protein's NTPase activity likely plays a role in replication, although it lacks helicase activity despite structural similarities. Protein P22 may also participate in targeting the replication complex to intracellular membranes. The viral genome-linked protein (VPg) is covalently attached to the 5'-end of positive- and negative-strand genomic RNAs and subgenomic RNA, functioning as a genome-linked replication primer. It may also recruit ribosomes to viral RNA, thereby enhancing viral protein translation. The 3C-like protease processes the polyprotein; 3CLpro-RdRp is initially released via autocleavage, followed by cleavage of other proteins. It may cleave host polyadenylate-binding protein, potentially inhibiting cellular translation. The RNA-dependent RNA polymerase (RdRp) replicates genomic and antigenomic RNA by recognizing replication-specific signals. It also transcribes a subgenomic mRNA by initiating internal RNA synthesis on the antigenomic RNA, encoding structural proteins. Finally, it catalyzes the covalent attachment of VPg to viral RNAs.
Gene References Into Functions
  1. A computational study elucidated the metal-binding preferences of the norovirus RNA-dependent RNA polymerase. PMID: 28383118
  2. Protease processing at ORF1 cleavage sites is primarily regulated by the P4-P2' sequences. PMID: 24991013
  3. X-ray crystallography of a Norwalk virus protease construct revealed that the C-terminal tail (representing native substrate positions P5 to P1) inserts into the active site cleft of a neighboring protease molecule. PMID: 23365454
  4. The proteases of Norwalk virus and MD145 exhibited similar cleavage efficiency on various substrates. PMID: 22200497
Database Links

KEGG: vg:1491970

Subcellular Location
[Protein p48]: Host membrane; Single-pass membrane protein.; [NTPase]: Host membrane; Single-pass membrane protein.; [Protein p22]: Host membrane; Single-pass membrane protein.

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