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Title: Functional Analysis of Conserved Motifs in Influenza Virus PB1 Protein

Journal Article · · PLoS ONE
 [1];  [1];  [1];  [2];  [1];  [1];  [1];  [3]
  1. University of Wisconsin, Madison, WI (United States)
  2. Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
  3. Univ. of Wisconsin, Madison, WI (United States); University of Tokyo (Japan)
+ Show Author Affiliations

The influenza virus RNA polymerase complex is a heterotrimer composed of the PB1, PB2, and PA subunits. PB1, the catalytic core and structural backbone of the polymerase, possesses four highly conserved amino acid motifs that are present among all viral RNA-dependent RNA polymerases. A previous study demonstrated the importance of several of these conserved amino acids in PB1 for influenza polymerase activity through mutational analysis. However, a small number of viruses isolated in nature possesses non-consensus amino acids in one of the four motifs, most of which have not been tested for their replicative ability. Here, we assessed the transcription/replication activities of 25 selected PB1 mutations found in natural isolates by using minireplicon assays in human and avian cells. Most of the mutations tested significantly reduced polymerase activity. One exception was mutation K480R, observed in several pandemic (H1N1) 2009 viruses, which slightly increased polymerase activity relative to wild-type. However, in the background of the pandemic A/California/04/2009 (H1N1) virus, this mutation did not affect virus titers in cell culture. Our results further demonstrate the functional importance of the four conserved PB1 motifs in influenza virus transcription/replication. The finding of natural isolates with non-consensus PB1 motifs that are nonfunctional in minireplicon assays suggests compensatory mutations and/or mixed infections which may have ‘rescued’ the inactive PB1 protein.

Research Organization:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Biological and Environmental Research (BER); Pfizer Animal Health
Grant/Contract Number:
AC52-06NA25396
OSTI ID:
1627511
Journal Information:
PLoS ONE, Vol. 7, Issue 5; ISSN 1932-6203
Publisher:
Public Library of ScienceCopyright Statement
Country of Publication:
United States
Language:
English

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Cited By (11)

The RNA-dependent RNA polymerase of the influenza A virus journal September 2014
Genetic and codon usage bias analyses of polymerase genes of equine influenza virus and its relation to evolution journal August 2017
Common and unique features of viral RNA-dependent polymerases journal August 2014
Common and unique features of viral RNA-dependent polymerases. text January 2014
Amino Acid Changes in the Influenza A Virus PA Protein That Attenuate Avian H5N1 Viruses in Mammals journal September 2014
Amino Acid Substitutions in PB1 of Avian Influenza Viruses Influence Pathogenicity and Transmissibility in Chickens journal July 2014
High-throughput profiling of influenza A virus hemagglutinin gene at single-nucleotide resolution journal May 2014
Integrating computational modeling and functional assays to decipher the structure-function relationship of influenza virus PB1 protein journal November 2014
Glycine at Position 622 in PB1 Contributes to the Virulence of H5N1 Avian Influenza Virus in Mice journal February 2016
Annotating Protein Functional Residues by Coupling High-Throughput Fitness Profile and Homologous-Structure Analysis journal December 2016
Functional Constraint Profiling of a Viral Protein Reveals Discordance of Evolutionary Conservation and Functionality journal July 2015

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59 BASIC BIOLOGICAL SCIENCES
polymerases
microbial mutation
sequence motif analysis
H5N1
influenza A virus
viral replication
influenza viruses
H1N1