Photo of Dr. Ernest Kwok.

Ernest Kwok

Assistant Professor

Ph.D.  Cornell University

email: ernest.kwok@csun.edu
Phone: (818) 677-3383
Fax: (818) 677-2034
Office: Citrus Hall 3218

Lab Page: http://www.csun.edu/~ekwok

I am studying the relationship between organelle morphology/location and cellular physiology in plant cells.  Of primary interest is the structure and function of plastid stromules.  Stromules (for stroma tubules) are thin projections of the outer and inner envelope membrane of plastids (including chloroplasts).  These structures are highly dynamic, changing shape and length rapidly.  Because of their small diameter, stromules are very difficult to observe using conventional bright field microscopy.  Stromules are best observed using fluorescent proteins that accumulate in the aqueous interior of plastids: the stroma.  Previous work identified proteins that inhabit the interior of stromules and investigated the relationship between stromules and the cytoskeleton.  At present, the function of these structures is unknown.  However, their ability to increase the surface area/volume ratio of the plastid suggests they may be involved in exchange of metabolites/membrane components with the cytosol or other organelles.  Currently, my lab is trying to determine the relationship between stromule formation and plastid division and the cell cycle.  This work is being conducted in Tobacco and Arabidopsis, using suspension cell cultures.

Additional Academic History:

B.S.  Harvey Mudd College

Representative Publications:

Holzinger A, Kwok EY, and Hanson MR.  [2008]  Effects of arc3, arc5, and arc6 mutations on plastid morphology and stromule formation in green and nongreen tissues of Arabidopsis thaliana.  Photochemistry and Photobiology 84[6]: 1324-1335.

Kwok EY, Severance S, and Kosman DJ (2006) Evidence for iron channeling in the Fet3p, Ftr1p high affinity iron uptake complex in the yeast plasma membrane.  Biochemistry 45(20): 6317-6327.

Kwok EY, Stoj C, Severance S, and Kosman DJ (2006) An engineered bifunctional high affinity iron uptake protein in the yeast plasma membrane.  Journal of Inorganic Biochemistry 100(5-6): 1053-1060.

Kwok EY and Kosman DJ (2006) Iron in yeast: Mechanisms involved in homeostasis.  Topics in Current Genetics 14: 59-99. 

Kwok EY and Hanson MR (2004) Stromules and the dynamic nature of plastid morphology.  Journal of Microscopy 214(2): 124-137.

Kwok EY and Hanson MR (2004) GFP-labeled Rubisco and aspartate aminotransferase are present in plastid stromules and traffic between plastids.  Journal of Experimental Botany 55(397):595-604.

Kwok EY and Hanson MR (2004) In vivo analysis of interactions between GFP-labeled microfilaments and plastid stromules.  BMC Plant Biology 4:2.

Kwok EY and Hanson MR (2004) Plastids and stromules interact with the nucleus and cell membrane in vascular plants.  Plant Cell Reports 23(4):188-95.

Kwok EY and Hanson MR (2003) Microfilaments and microtubules control the morphology and movement of non-green plastids and stromules in Nicotiana tabacum. Plant Journal 35(1):16-26.