SARS-unique fold in the Rousettus bat coronavirus HKU9

Area of Science:

• Structural biology
• Virology
• Biochemistry

Background:

• Coronavirus nonstructural protein 3 (nsp3) is multifunctional, aiding viral polyprotein cleavage and immune interference.
• The "SARS-unique" region of SARS-CoV nsp3 has been proposed to be conserved in other coronaviruses.

Purpose of the Study:

• To determine the solution NMR structure of a SARS-unique region protein from bat coronavirus HKU9.
• To investigate the structural conservation and potential functions of this region in betacoronaviruses.

Main Methods:

• Solution Nuclear Magnetic Resonance (NMR) spectroscopy
• Bioinformatics analysis
• Biochemical analysis

Main Results:

• The solution NMR structure of the bat coronavirus HKU9 "SARS-unique" region protein was determined.
• The protein exhibits a frataxin fold (α+β), similar to SARS-CoV nsp3.
• A conserved functional site was identified through bioinformatics and biochemical studies.

Conclusions:

• The "SARS-unique" region is conserved among various coronavirus phylogenetic groups, not unique to SARS-CoV.
• This region likely provides essential functions in viral replication or transcription.
• The determined structure provides experimental evidence for the conserved nature and potential importance of this nsp3 domain.