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postdocdoral position

Elsbeth Walker ewalker at bio.umass.edu
Thu Jun 21 11:57:54 EST 2001

University of Massachusetts, Amherst

NSF-supported postdoctoral positions are available for a period of 
three years to study the function of the eight members of the Yellow 
Stripe-Like (YSL) family of Arabidopsis.  YSL family members were 
identified based on their very strong sequence similarity to the YS1 
protein of maize (Curie et al, 2001. Nature 409:346-349.).  The 
function of maize YS1 is in the primary uptake of iron from the soil. 
However, unlike other known plant iron transporters, YS1 transports 
iron that is complexed by specific plant-derived Fe(III) chelators 
called phytosiderophores.  There are eight YSL proteins encoded in 
the Arabidopsis thaliana genome 
(http://www.bio.umass.edu/biology/ewalker), but they cannot function 
in phytosiderophore uptake, since Arabidopsis (like all non-grasses) 
can neither synthesize nor use phytosiderophores.  Arabidopsis does 
make and use a related compound, nicotianamine, which is the 
biosynthetic precursor to phytosiderophores. Preliminary evidence 
suggests that YSL proteins mediate transport of metals bound to 
nicotianamine.  The many roles of nicotianamine in achieving proper 
metal ion allocation in plants are incompletely understood, but there 
is strong evidence that nicotianamine is necessary for distribution 
of Fe, Zn, and Mn via phloem, and that it is required for transport 
of Cu in xylem.  For the current project, the functions of the eight 
Arabidopsis thaliana YSL genes will be determined from the narrowest 
definition of function-biochemical function, to the broadest 
definition of function-the role of these proteins in the growth and 
development of the plant. By integrating this information for all 
eight YSL genes, we will improve our understanding of metal ion 
allocation mechanisms used by plants, and further the goal of 
manipulating plant metal allocation for the purposes of 
phytoremediation and improved value for human nutrition.

Please send a letter of application, CV, a set of reprints and 
preprints, and names, addresses and email addresses of 3 references 
to Elsbeth Walker, Biology  Dept., 611 North Pleasant St., University 
of Massachussets, Amherst, MA 01003.  Ph: 413-545-0861;  fax: 413 
545-3243;  e-mail: ewalker at bio.umass.edu.

I will be available at the American Society of Plant Biologists 
Meeting (July 21 to July 25, Providence, RI) to discuss possible 
projects with interested candidates.
"The noble simplicity in the works of nature only too often 
originates in the noble shortsightedness of the one who observes it." 
-Geor Lichtenberg, 1784

Elsbeth L. Walker		611 N. Pleasant St.
Assistant Professor		University of Mass, Amherst
Biology Department		Amherst, MA 01003
(413) 545-0861 voice		(413) 545-3243 fax

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