Gene

Coronavirus

2019-20 coronavirus outbreak

Cell biology

Stop codon

Sars virus

Biology

Messenger RNA

Spike Protein

Open reading frame

Virology

Structural protein

Biochemistry

Protein structure

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)

Plasma protein binding

Outbreak

Computational biology

Coronavirus disease 2019 (COVID-19)

Translation (biology)

Start codon

Genetics

Infectious disease (medical specialty)

Medicine

Chemistry

Virus

Peptide sequence

Disease

Pathology

Severe acute respiratory syndrome coronavirus

Structure

To achieve the greatest output from their limited genomes, viruses frequently make use of alternative open reading frames, in which translation is initiated from a start codon within an existing gene and, being out of frame, gives rise to a distinct protein product. These alternative protein products are, as yet, poorly characterized structurally. Here we report the crystal structure of ORF-9b, an alternative open reading frame within the nucleocapsid (N) gene from the SARS coronavirus. The protein has a novel fold, a dimeric tent-like β structure with an amphipathic surface, and a central hydrophobic cavity that binds lipid molecules. This cavity is likely to be involved in membrane attachment and, in mammalian cells, ORF-9b associates with intracellular vesicles, consistent with a role in the assembly of the virion. Analysis of ORF-9b and other overlapping genes suggests that they provide snapshots of the early evolution of novel protein folds.

The Crystal Structure of ORF-9b, a Lipid Binding Protein from the SARS Coronavirus