Findings Reveal Clues to Functioning of
Researchers have discovered the structure of a key protein on the surface of an
unusually large virus called the “mimivirus,” aiding efforts to determine its hosts
and unknown functions.
The mimivirus was initially thought to be a bacterium
because it is much larger than most viruses. It was isolat-
ed by French scientists in 1992 but wasn’t confirmed to
be a virus until 2003.
In the laboratory, the virus has been studied while
infecting amoebas, but its natural hosts in the wild and
many details about the virus remain unknown, says
Michael Rossmann, the Hanley Distinguished Professor
of Biological Sciences.
He led a team of researchers who discovered the struc-
ture of a key, enzyme-like protein called R135, which
is contained in fibers on the outer surface of the virus.
The structure of R135 is similar to an enzyme called aryl alcohol oxidase, which is
found in a fungus and is involved in biodegrading lignin in plant cell walls.
“This could tell us something about the mimivirus’s natural hosts,” says Rossmann,
whose research was funded by the National Institute for Allergies and Infectious
diseases. “We think there must
be another host, something
different than amoebas and that
this enzyme helps the virus get
into this host. Perhaps R135
participates in the degradation of
lignin so that the virus can enter
a host such as lignin-containing
Also suggesting the possibility of alternative hosts is the
recent discovery that mimivirus
has been found to be abundant
in oysters. Antibodies against
mimivirus have been found in
humans, and the virus has been
discovered inside specialized
cells in humans called macrophages, but whether it actually
infects people is not known.
“I wouldn’t say it infects humans,
but it can propagate in humans because macrophages take up this virus and it can
propagate in these,” says Thomas Klose, an assistant research scientist at Purdue
working with Rossmann. “Overall, there are many unknowns.”
Research findings appeared in the June 2 issue of the journal Structure.
This graphic shows the location of a key protein called R135,
contained in fibers on the outer surface of an unusually large virus
called the mimivirus. Findings by Purdue researchers are aiding
efforts to learn more about the mysterious virus, including its
hosts and unknown functions. (Klose et al./Structure 2015)
Purdue Startup Develops
A Purdue University researcher and entrepreneur is commercializing her laboratory’s innovative collagen formulations
that self-assemble or polymerize to form
fibrils that resemble those found in the
Sherry Harbin’s collagen building blocks
can be used to create customized three-dimensional tissue and organs outside the
body to support basic biological research,
drug discovery and chemical toxicity
testing. They also can be used to create
next generation tissue engineered medical products that foster improved tissue
integration and regeneration.
Harbin, an associate professor in Purdue’s
Weldon School of Biomedical Engineering and Department of Basic Medical
Sciences, and founder of GeniPhys, has
worked for more than 10 years to tap into
the secrets of the extracellular matrix, a
3D meshwork of molecules or microenvironment, including collagen, within which
cells live and function in the body.
The result is engineered collagen polymer.
Since the engineered tissue matrix is
designed at the molecular level, it can be
customized in terms of geometry, fibril
microstructure, mechanical properties
and cell-instructive capacity.
“In this way, scientists can determine
how specific attributes of the collagen
ECM affect cell behavior, including tumor
metastasis and drug/toxin sensitivity,”