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SABEEHA MERCHANT |
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Biochemistry and Molecular Genetics of Metal Metabolism
My research program encompasses four related projects: one dealing with the mechanism of signal transduction in the context of copper homeostasis, another dealing with iron metabolism, a third dealing with the mechanism of assembly of membrane-associated heme proteins, and a new project concerned with the cell biology of a key enzyme in chlorophyll biosynthesis, the aerobic cyclase.
A large fraction of proteins require metals (e.g. Zn, Cu, Fe, Mn) or metal-cofactors (hemes, FeS centers, chlorophylls, cobalamin, molybdopterin) for function. The metal is invariably an important structural constituent of the protein, and it is essential for function in the proteins where it serves a catalytic role. Metals and metal cofactors are found in every cellular compartment and they function in diverse metabolic pathways. In one genome (of a photosynthetic microorganism), cofactor/prosthetic group metabolism accounts for as much as 12% of its function. The chemical reactivity, exploited in biology to make desirable catalysts, can cause intracellular damage if it is not controlled. Metal metabolism is, therefore, subject to tight homeostatic regulation.
My group is addressing basic questions related to metal and metal cofactor metabolism. How is the abundance / availability of a cofactor within the cell controlled? How is the cofactor distributed to various organelles? Is there a hierarchy of distribution when the cofactor might be limiting (as a result of genetic lesion or sub-optimal nutritional supply)? What are the mechanisms that ensure highly selective association between a polypeptide and its cofactor?
Our attention is focused on both inorganic (copper, iron) redox-active cofactors and tetrapyrrole cofactors (heme, chlorophyll) that are found in quantity in electron transfer pathways, such as respiration and photosynthesis. My program is based on our discoveries relating to the biogenesis of photosynthetic catalysts in chloroplasts.
For more information on our projects, chose copper , heme, iron, or chlorophyll.
Positions for Ph.D. students and post-doctoral scholars are available on all projects. Candidates with demonstrated research productivity (publication record) and expertise in genetics or biochemistry are especially encouraged to apply for post-doctoral positions. Ph.D. candidates should apply to the Department of Chemistry and Biochemistry,to ACCESS, or to the Molecular Toxicology Inter-departmental program. I participate also in the Plant Biology program.
59. Quinn, J.M., Eriksson, M., Moseley, J.L., Merchant, S. (2002) Oxygen Deficiency Responsive Gene Expression in Chlamydomonas reinhardtii through a Copper-Sensing Signal Transduction Pathway Plant Physiol. 128:463-471.
60. LaFontaine, S., Quinn, J.M., Merchant, S. (2002) Comparative analysis of copper and iron metabolism in photosynthetic eukaryotes versus yeasts and mammals, in Handbook of Copper Pharmacology and Toxicology, Humana Press, Inc., ed. E.J. Massaro: Totowa, N.J. 481-502.
61. Moseley, J.L., Page, M.D., Alder, N.P., Eriksson, M., Quinn, J., Soto, F., Theg, M., Hippler, M., Merchant, S. (2002) Reciprocal expression of two candidate di-iron enzymes affecting photosystem I and light-harvesting complex accumulation. Plant Cell 14:673-688.
62. LaFontaine, S., Quinn, J.M., Nakamoto, S.S., Page, M.D., Göhre, V., Moseley, J.L., Kropat, J., Merchant, S. (2002) Copper-Dependent Iron Assimilation Pathway in the Model Photosynthetic Eukaryote Chlamydomonas reinhardtii. Eukaryotic Cell 1(5):736-757.
63. Moseley, J., Allinger, T., Herzog, P., Wehinger, E., Merchant, S., Hippler, M. (2002) Adaptation to Fe-deficiency requires re-modelling of the photosynthetic apparatus. EMBO J. 21: 6709-6720.
64. Dreyfuss, B.W., Hamel, P., Nakamoto, S.S., Merchant, S. (2003) Functional analysis of a divergent system II protein, Ccs1, involved in c-type cytochrome biogenesis. J. Biol. Chem. 278: 2604-2613.
65. Hamel, P., Dreyfuss, B.W., Xie, Z., Gabilly, S., Merchant, S. (2003) Essential histidine and tryptophan residues in CcsA, a system II polytopic cytochrome c biogenesis protein. J. Biol. Chem. 278: 2593-2603.
50. Koehler, C.M., Leuenberger, D., Merchant, S., Renold, A., Junne, T., Schatz, G. (1999) Human Deafness Dystonia Syndrome is a Mitochondrial Disease. Proc. Natl. Acad. Sci USA 96:2141-2146. see commentary
56. Springer, S., Chen, E., Duden, R., Marzioch, M., Rowley, A., Hamamoto, S., Merchant, S., Schekman, R. (2000) The p24 proteins are not essential for vesicular transport in Saccharomyces cerevisiae. Proc. Natl. Acad. Sci. USA 97:4034-4039. see commentary.
310-206-1035 
310-825-8300
To request materials for application to a Ph.D. program in life sciences at UCLA, click here. (Please note you may not be able to return to this page by clicking the "back" button. If you are using Netscape, choose "go" from the menu and select the Merchant webpage to return.)
GROUP MEMBERS - Merchant Group Resources
Former Ph.D. Students- 1991
- 1993
- 1994
- 1998
- 2000
- 2001
- 2002
Former Post-doctoral Scholars
Ute Boronowsky - utebo@nikocity.de
Duane Culler
Beth Dreyfuss - dreyfuss@chem.ucla.edu
Mats Eriksson - mats.eriksson@plantphys.umu.se
Sharon La Fontaine - sharonl@deakin.edu.au
- Visit with Sharon
M. Dudley Page - dpage@chem.ucla.edu
Tomas Westergren - tomwest@chem.ucla.edu
Jeanette Quinn - jeanette_quinn@stratagene.com
Former Visitors
Paola Barraco -- Paola
and Luca got married
Ph.D. Students presently
in the group
Michael Allen - mallen278@mindspring.com
- Michael's
Project
Delphine Bernard - delphine@chem.ucla.edu
Post-doctoral Scholars presently in the group
Jose del Campo - delcampo@chem.ucla.edu
Maria Felix Vazquez-Bermudez - mvazber@yahoo.es
Patrice Hamel - hamel@chem.ucla.edu
- Patrice
wins Boyer Award - March 2003
Janette Kropat - kropat@chem.ucla.edu
Stephen Tottey - tottey@chem.ucla.edu
Technicians
Elida Escalante - elidae@chem.ucla.edu
Stephane Gabilly - gabilly@chem.ucla.edu
Undergraduates
Rotation Students
MERCHANT
LAB COLLABORATORS
Present
Deb Berthold - berthold@dbb.su.se
- on structural analysis of Crd1
Maryse Block - block@dsvsud.cea.fr
- on localization of chlorophyll biosynthesis enzymes
David Bollivar- dbolliva@titan.iwu.edu
Jean-Pierre Carde -jean-pierre.carde@bordeaux.inra.fr
- on localization of chlorophyll biosynthesis enzymes
Ken Cline - kcline@ufl.edu - on localization
of chlorophyll biosynthetic enzymes
Genevieve Dujardin - dujardin@cgm.cnrs-gif.fr
- on mitochondrial cytochrome biogenesis
Michael Hippler - m.hippler@uni-jena.de
- on molecular responses to Fe-deficiency
Poul Erik Jensen - peje@kvl.dk - on
the aerobic oxidative cyclase in chlorophyll biosynthesis
Saul Purton -
s.purton@ucl.ac.uk - on b cytochrome biogenesis
Krishna Niyogi
- niyogi@nature.berkeley.edu
- on Chlamydomonas microarrays
Steve Theg- smtheg@ucdavis.edu
- on localization of plastid proteins
Chris
Vulpe - vulpe@uclink4.berkeley.edu
- on Chloamydomonas microarrays
Francis-Andre Wollman - wollman@ibpc.fr
- on b and c type cytochrome mutants
Past
Dan Kosman - on copper uptake
Laurie Mets - l-mets@uchicago.edu
- on genetic analysis of plastocyanin and cytochrome mutants
Todd Yeates - yeates@mbi.ucla.edu
- on structural analysis of plastocyanin and cytochrome c6
| PHOTOS AT MEETINGS | OTHER PHOTOS |
| Brisbane,
Australia 2001 Lake Tahoe 2002 Joshua Tree 2003 Embo Workshop 2003 Gordon Research Conference 2003 Ischia 2003 |
2003 UCLA Plant Biology |
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