||December 22, 2008
||Dr. Hiroyuki Ogata, Structural and Genomic Information, CNRS, Marseille
||Host-like genes in giant DNA viruses
Recent discoveries of several "host-like" genes in aquatic viruses start to uncover
a potentially large spectrum of viral strategies in manipulating host metabolism.
I'll first present two remarkable cases of "host-like" genes that we recently encountered:
(1) The nblA, encoding light-harvesting antenna degradation enzyme, found in the Ma-LMM01
phage that infects the toxic cyanobacteria Microcystis aeruginosa, and (2) a series of
sphingolipid biosynthesis enzyme genes found in the large Emiliania huxleyi viruses, very likely
transferred from their eukaryotic host microalga. These results suggest a significant role of
horizontal gene transfer (HGT) in viral genome evolution. Next, I'll present several
bioinformatics results from our group, suggesting that the viral gene pool is substantially
isolated from the cellular gene pool, and that "host-to-virus" HGTs are not as frequent as
often thought. This reinforces the idea that "host-to-virus" HGTs may be rare evolutionary
events and therefore likely reflect important aspects of host-virus interactions. Finally, I'll
present our new bioinformatics approach ("phylogenetic mapping"), which revealed the
abundance of the giant Mimiviruses in oceanic environments, as a way to characterize
the yet uncovered hugely diverse virosphere.
1. Ogata H, Claverie J.-M. How to infect a Mimivirus. Science 321, 1305-1306 (2008).
2. Monier A., Claverie J.-M., Ogata H. Taxonomic distribution of large DNA viruses in the sea.
Genome Biol., 9, R106 (2008).
3. Yoshida T., Nagasaki K., Takashima Y., Shirai Y., Tomaru Y., Takao Y., Sakamoto S., Hiroishi S., Ogata H.
Ma-LMM01 infecting toxic Microcystis aeruginosa illuminates diverse cyanophage genome strategies.
J. Bacteriol., 190, 1762-1772 (2008).
4. Monier A., Claverie J.-M., Ogata H. Horizontal gene transfer and nucleotide compositional anomaly in
large DNA viruses. BMC Genomics, 8, 456 (2007).
5. Ogata H., Claverie J.-M. Unique genes in giant viruses: regular substitution pattern and anomalously short size.
Genome Res. 17, 1657-1664 (2007).