  The 2019 novel coronavirus (2019-nCoV) is currently causing a widespread
outbreak centered on Hubei province, China and is a major public health
concern. Taxonomically 2019-nCoV is closely related to SARS-CoV and
SARS-related bat coronaviruses, and it appears to share a common receptor with
SARS-CoV (ACE-2). Here, we perform structural modeling of the 2019-nCoV spike
glycoprotein. Our data provide support for the similar receptor utilization
between 2019-nCoV and SARS-CoV, despite a relatively low amino acid similarity
in the receptor binding module. Compared to SARS-CoV, we identify an extended
structural loop containing basic amino acids at the interface of the receptor
binding (S1) and fusion (S2) domains, which we predict to be
proteolytically-sensitive. We suggest this loop confers fusion activation and
entry properties more in line with MERS-CoV and other coronaviruses, and that
the presence of this structural loop in 2019-nCoV may affect virus stability
and transmission.
