My background is in biophysics. My Ph.D. work at Ohio State University involved
the use of circular dichroism spectroscopy and various biochemical
modifications to study the mechanism by which changes in conformation
of the membrane protein, bacteriorhodopsin, could allow it to pump
protons out of the cell. My studies convinced me that the rigidity
of the lipid membrane surrounding the protein was important in
determining whether the protein could undergo the required conformational
changes.
I
subsequently did a postdoc in a physical chemistry lab at the
University of Arizona in which I investigated the effect
of membrane lipid headgroup and acyl chain composition on the
function of another membrane protein, bovine rhodopsin. My work
with rhodopsin
convinced me that many membrane proteins depend on a complex
mixture of lipid headgroup size and charge, and on acyl chain length and
unsaturation, for normal functioning. Basically, membrane lipid
composition will determine the degree to which the membrane resists
or assists the protein in undergoing necessary conformational
changes. Furthermore, this explains how cell signaling can be
accomplished by phospholipases,
which release fatty acids to a cell surface, thereby altering
the membrane's properties and subsequently a protein's state.
This
appeared to be very important in cells of the nervous system,
so I joined the ARLDN in order to improve my understanding of
that
system. My focus has shifted from biophysical interactions in
the membrane to questions of development of brain structure,
particularly
axon guidance. My current efforts (spanning the Hildebrand, Tolbert,
and Nighorn labs) include studies of the role of nitric oxide
synthase
in formation of the brain during metamorphosis in Manduca sexta
(Fig 1), as well as the role played by downstream effectors of
NO including soluble guanylyl cyclase (Fig 2) and NO-induced
acylation, glycosylation, nitrosylation, and ADP-ribosylation
of proteins.
In particular, I am studying the mechanisms by which NO can affect
cell migration and growth cone outgrowth by using drugs which
block particular biochemical pathways known to be modulated by
NO.
Other
work currently underway involves the biochemical and molecular
biological characterization
of proteins (and possibly lipids) responsible for the sexually
dimorphic architecture of the primary olfactory centers of
the Manduca brain. I am working toward isolating proteins/lipids
unique to the male pheromone-responsive olfactory receptor
cells
based
on attached carbohydrate residues (Fig 3).
Selected Publications
Gibson NJ, Nighorn A (2000) Expression of nitric oxide synthase
and soluble guanylyl cyclase in the developing olfactory system
of Manduca sexta. J Comp Neurol, in press.
Nighorn A, Gibson NJ, Rivers D,Hildebrand JG, Morton DB (1998)
The nitric oxide-cGMP pathway may mediate communication between
sensory afferents and projection neurons in the antennal lobe of
Manduca sexta. J Neurosci 18(18), 7244-7255.
Gibson NJ, Brown MF (1992) Lipid headgroup and acyl chain composition
modulate the MI_MII equilibrium of rhodopsin in recombinant membranes.
Biochemistry 32:2438-2454.
Brown
MF, Gibson NJ (1992) Biological function of docosahexaenoic acid
in the retinal rod disk membrane. In: Sinclair A, Gibson
R (eds) Proc Third Internat Cong Essential Fatty Acids & Eicosanoids,
pp 134-138.
Gibson NJ, Brown MF (1991) Membrane lipid influences on the energetics
of the MI and MII conformational states of rhodopsin probed by
flash photolysis. Photochem Photobiol 54:985-992.
Gibson NJ, Cassim JY (1989) Evidence for an alpha II-type helical
conformation for bacteriorhodopsin in the purple membrane. Biochemistry
28: 2134-2139.
Gibson NJ, Cassim JY (1989) Nature of forces stabilizing the transmembrane
protein bacteriorhodopsin in purple membrane. Biophys J 56:769-780.
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