Journal of Biological Chemistry,
Journal Year:
2024,
Volume and Issue:
300(8), P. 107514 - 107514
Published: June 28, 2024
The
development
of
safe
and
effective
broad-spectrum
antivirals
that
target
the
replication
machinery
respiratory
viruses
is
high
priority
in
pandemic
preparedness
programs.
Here,
we
studied
mechanism
action
a
newly
discovered
nucleotide
analog
against
diverse
RNA-dependent
RNA
polymerases
(RdRps)
prototypic
viruses.
GS-646939
active
5'-triphosphate
metabolite
4'-cyano
modified
C-adenosine
phosphoramidate
prodrug
GS-7682.
Enzyme
kinetics
show
RdRps
human
rhinovirus
type
16
(HRV-16)
enterovirus
71
incorporate
with
unprecedented
selectivity;
incorporated
20-50-fold
more
efficiently
than
its
natural
ATP
counterpart.
RdRp
complex
syncytial
virus
metapneumovirus
similar
efficiency.
In
contrast,
influenza
B
shows
clear
preference
for
mitochondrial
polymerase
does
not
significant
incorporation
GS-646939.
Once
into
nascent
strand,
acts
as
chain
terminator
although
higher
NTP
concentrations
can
partially
overcome
inhibition
some
polymerases.
Modeling
biochemical
data
suggest
4'-modification
inhibits
translocation.
Comparative
studies
GS-443902,
triphosphate
form
1'-cyano
prodrugs
remdesivir
obeldesivir,
reveal
only
different
mechanisms
inhibition,
but
also
differences
spectrum
viral
conclusion,
modifications
analogs
provide
complementary
strategies
to
several
families
Viruses,
Journal Year:
2024,
Volume and Issue:
16(4), P. 546 - 546
Published: March 31, 2024
Remdesivir
(RDV)
is
a
broad-spectrum
nucleotide
analog
prodrug
approved
for
the
treatment
of
COVID-19
in
hospitalized
and
non-hospitalized
patients
with
clinical
benefit
demonstrated
multiple
Phase
3
trials.
Here
we
present
SARS-CoV-2
resistance
analyses
from
SIMPLE
studies
evaluating
RDV
participants
severe
or
moderate
disease.
The
enrolled
radiologic
evidence
pneumonia
room-air
oxygen
saturation
≤94%
>94%,
respectively.
Virology
sample
collection
was
optional
study
protocols.
Sequencing
related
viral
load
data
were
obtained
retrospectively
at
subset
sites
local
sequencing
capabilities
(10
183
sites)
timepoints
detectable
load.
Among
both
baseline
post-baseline
treated
RDV,
emergent
Nsp12
substitutions
observed
4
19
(21%)
none
2
study.
following
5
emerged:
T76I,
A526V,
A554V,
E665K,
C697F.
C697F
had
an
EC50
fold
change
≤1.5
relative
to
wildtype
reference
using
subgenomic
replicon
system,
indicating
no
significant
susceptibility
RDV.
phenotyping
E665K
could
not
be
determined
due
lack
replication.
These
reveal
relevant
emergence
further
confirm
established
efficacy
profile
high
barrier
patients.
Journal of Virology,
Journal Year:
2023,
Volume and Issue:
97(6)
Published: May 18, 2023
Coronavirus
genome
replication
and
expression
are
mediated
by
the
viral
replication-transcription
complex
(RTC)
which
is
assembled
from
multiple
nonstructural
proteins
(nsp).
Among
these,
nsp12
represents
central
functional
subunit.
It
harbors
RNA-directed
RNA
polymerase
(RdRp)
domain
contains,
at
its
N
terminus,
an
additional
called
NiRAN
widely
conserved
in
coronaviruses
other
nidoviruses.
In
this
study,
we
produced
bacterially
expressed
coronavirus
nsp12s
to
investigate
compare
NiRAN-mediated
NMPylation
activities
representative
alpha-
betacoronaviruses.
We
found
that
four
domains
characterized
date
have
a
number
of
properties,
including
(i)
robust
nsp9-specific
appear
operate
largely
independently
C-terminal
RdRp
domain,
(ii)
nucleotide
substrate
preference
for
UTP
followed
ATP
nucleotides,
(iii)
dependence
on
divalent
metal
ions,
with
Mn2+
being
preferred
over
Mg2+,
(iv)
key
role
N-terminal
residues
(particularly
Asn2)
nsp9
efficient
formation
covalent
phosphoramidate
bond
between
NMP
amino
group
nsp9.
context,
mutational
analysis
confirmed
conservation
critical
Asn2
across
different
subfamilies
family
Coronaviridae,
as
shown
studies
using
chimeric
variants
six
were
replaced
those
corona-,
pito-
letovirus
homologs.
The
combined
data
previous
reveal
remarkable
degree
among
activities,
supporting
enzymatic
activity
synthesis
processing.
IMPORTANCE
There
strong
evidence
large
nidoviruses
evolved
unique
RdRp-associated
but
not
most
viruses.
Previous
mainly
focused
severe
acute
respiratory
syndrome
2
(SARS-CoV-2)
suggested
functions
such
NMPylation/RNAylation
nsp9,
guanylyltransferase
involved
canonical
and/or
unconventional
capping
pathways,
functions.
To
help
resolve
partly
conflicting
information
specificities
ion
requirements
reported
previously
SARS-CoV-2
activity,
extended
these
earlier
characterizing
betacoronavirus
domains.
study
revealed
features
protein
specificity
requirements,
very
well
genetically
divergent
coronaviruses,
suggesting
potential
avenues
future
antiviral
drug
development
targeting
essential
enzyme.
Journal of Biological Chemistry,
Journal Year:
2024,
Volume and Issue:
300(8), P. 107514 - 107514
Published: June 28, 2024
The
development
of
safe
and
effective
broad-spectrum
antivirals
that
target
the
replication
machinery
respiratory
viruses
is
high
priority
in
pandemic
preparedness
programs.
Here,
we
studied
mechanism
action
a
newly
discovered
nucleotide
analog
against
diverse
RNA-dependent
RNA
polymerases
(RdRps)
prototypic
viruses.
GS-646939
active
5'-triphosphate
metabolite
4'-cyano
modified
C-adenosine
phosphoramidate
prodrug
GS-7682.
Enzyme
kinetics
show
RdRps
human
rhinovirus
type
16
(HRV-16)
enterovirus
71
incorporate
with
unprecedented
selectivity;
incorporated
20-50-fold
more
efficiently
than
its
natural
ATP
counterpart.
RdRp
complex
syncytial
virus
metapneumovirus
similar
efficiency.
In
contrast,
influenza
B
shows
clear
preference
for
mitochondrial
polymerase
does
not
significant
incorporation
GS-646939.
Once
into
nascent
strand,
acts
as
chain
terminator
although
higher
NTP
concentrations
can
partially
overcome
inhibition
some
polymerases.
Modeling
biochemical
data
suggest
4'-modification
inhibits
translocation.
Comparative
studies
GS-443902,
triphosphate
form
1'-cyano
prodrugs
remdesivir
obeldesivir,
reveal
only
different
mechanisms
inhibition,
but
also
differences
spectrum
viral
conclusion,
modifications
analogs
provide
complementary
strategies
to
several
families
