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1. The Plant Cell, Vol. 25: 3022–3038, August 2013, www.plantcell.org  2013 American Society of Plant Biologists

Identification of Myosin XI Receptors in Arabidopsis Defines a Distinct Class of Transport Vesicles Valera V. Peremyslov,a Eva A. Morgun,a,b Elizabeth G. Kurth,a Kira S. Makarova,c Eugene V. Koonin,c and Valerian V. Doljaa
a Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon 97331
b Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742
c National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland 20894

To characterize the mechanism through which myosin XI-K attaches to its principal endomembrane cargo, a yeast twohybrid library of Arabidopsis thaliana cDNAs was screened using the myosin cargo binding domain as bait. This screen
identified two previously uncharacterized transmembrane proteins (hereinafter myosin binding proteins or MyoB1/2) that share a myosin binding, conserved domain of unknown function 593 (DUF593). Additional screens revealed that MyoB1/2 also bind myosin XI-1, whereas myosin XI-I interacts with the distantly related MyoB7. The in vivo interactions of MyoB1/2 with myosin XI-K were confirmed by immunoprecipitation and colocalization analyses. In epidermal cells, the yellow fluorescent protein–tagged MyoB1/2 localize to vesicles that traffic in a myosin XI–dependent manner. Similar to myosin XI-K, MyoB1/2 accumulate in the tip-growing domain of elongating root hairs. Gene knockout analysis demonstrated that functional cooperation between myosin XI-K and MyoB proteins is required for proper plant development. Unexpectedly, the MyoB1-containing vesicles did not correspond to brefeldin A–sensitive Golgi and post-Golgi or prevacuolar compartments and did not colocalize with known exocytic or endosomal compartments. Phylogenomic analysis suggests that DUF593 emerged in primitive land plants and founded a multigene family that is conserved in all flowering plants. Collectively, these findings indicate that MyoB are membrane-anchored myosin receptors that define a distinct, plant-specific transport vesicle compartment.

Volume 3, Issue 5, October 2013, Pages 542–545

Accelerating expansion of the viral universe Editorial overview
Valerian V Dolja and Mart Krupovic1

1Department of Microbiology, Institut Pasteur,
75015 Paris, France

For two decades between 1985 and 2006, the field of virology seemed to be
defined by the Fields Virology that features encyclopedic coverage of the
viruses of humans and other animals, but barely touches on viruses infecting
other hosts such as bacteria or plants let alone archaea. Although this book
will continue to play a fundamental role in the education and training of
virologists, it hardly scratches the surface of the Virus World as we now come
to know it: almost every single concept previously held dear by the students
of viruses has been challenged or overturned by revolutionary new discoveries