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Postdoctoral position available in the lab of Winslow Briggs

Bratislav Stankovic braco_stankovic at ncsu.edu
Thu Mar 19 14:24:32 EST 1998


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A postdoctoral position is available in my laboratory starting any 
time soon, and I am particularly looking for somebody with experience 
in protein chemistry. An abstract of our current research follows.

SIGNAL TRANSDUCTION IN PHOTOTROPISM: IN PURSUIT OF AN ELUSIVE PHOTORECEPTOR

Eva Huala, John Christie, Paul Oeller, Emmanuel Liscum, In-Seob Han,
Elise Larsen, and Winslow R. Briggs 

Department of Plant Biology, Carnegie Institution of Washington, 260
Panama St., Stanford, CA 94305, USA

The NPH1  gene was previously hypothesized to encode the
photoreceptor for phototropism in Arabidopsis thaliana. On
irradiation with blue light it carries out autophosphorylation both
in vivo and in vitro. We have now sequenced both genomic and cDNA
clones for A. thaliana, cDNA clones of two NPH1 homologues from
Avena sativa and a cDNA clone from Zea mays. The A. thaliana genomic
sequence is unusual in that it is broken into 20 exons. The A.
thaliana gene encodes a protein of 996 amino acids, the A. sativa
genes proteins of 926 and 933 amino acids respectively. The deduced 
protein sequence for all three genes  has all eleven of the
conserved motifs found in serine/threonine kinases, as we predicted
earlier from biochemical experiments.  These are located near the
C-terminal end of the protein. The sequence also contains two
repeated domains of 107 amino acids (that we are currently
designating LOV1 and LOV2) that share significant homology with a
heterogeneous group of gene products from several non-plant
organisms: bat from Halobacterium halobium (Archaea); nifL from
Klebsiella pneumoniae,  Azotobacter vinelandii, and Enterobacter
agglomerans (Eubacteria), recently shown to be a flavoprotein in A.
vinelandii; aer from Escherichia coli (Eubacteria), also thought to
be a flavoprotein; wc-1 from Neurospora crassa (Fungi); and members
of the eag family from Drosophila, rat and man. The activities of
all of these proteins are regulated either by light, oxygen, or
voltage (hence LOV). The deduced NPH1 protein is also highly
homologous with three plant gene fragments (ice plant, pea, and
spinach) in GenBank that were obtained by using PCR on kinase
signature sequences. They have all of the kinase signature domains
found in the A. thaliana gene, all have at least the A1 domain, and
spinach, the longest fragment, clearly has the A2 domain as well.
The overall protein sequence similarity is extremely high. We are
investigating whether the LOV1 and LOV2 domains of NPH1 may function
as redox sensors, and whether they function as flavin-binding
domains. Autophosphorylation of NPH1 protein produced heterologously
by the Baculovirus/insect cell system is induced by blue light,
suggesting that the protein is acquiring a blue light-absorbing
chromophore, likely a flavin, from the insect cells, and that the
holoprotein is the photoreceptor for phototropism. We have named the
photoreceptor photokinase. 
(Note new street number, new area code!)
Winslow R. Briggs, 
Dept. Plant Biology, 
Carnegie Institution of Washington, 
260 Panama St., Stanford, California 94305
Phone (650) 325-1521 Ex 207
Fax (650) 325-6857
email briggs at andrew.stanford.edu





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