Campus

 

Rosemary Stuart

Professor
Wehr Life Sciences, 309
(414) 288-1472
E-mail

B.Sc., 1984, University College, Dublin, Ireland
M.Sc., 1985, University College, Dublin, Ireland
Dr. rer. nat., 1989, Ludwig-Maximillians Universität, München, Germany
Postdoctoral Fellow, Imperial Cancer Research Fund, London, U.K.
Dr. rer. biol. hum. Habil., 1998, Ludwig-Maximillians Universität, München, Germany


 

Mitochondrial Biogenesis using Yeast as a Model Organism - Introduction

Mitochondria play a pivotal role in the life of cells, controlling diverse processes ranging from energy production to ion homoeostasis, heme, lipid and amino acid biosynthesis and the regulation of cell death. In humans, numerous pathological conditions have been linked to mitochondrial dysfunction and defects in their oxidative phosphorylation (OXPHOS) capacity. The activity of the mitochondrial respiratory chain protein complexes is primarily or secondarily affected in OXPHOS metabolism diseases, which in turn leads to impaired oxygen utilization, reduced energy (ATP) production and generation of oxidative stress conditions leading to the production of reactive oxygen species (ROS). The research in my laboratory is focused on understanding the protein composition and process of assembly of the mitochondrial respiratory chain (OXPHOS) complexes.

Elucidating the assembly pathway of mitochondrial ribosomes (NSF funded)

Mitochondrial ribosomes synthesize a small, but functionally important subset of proteins, which include some subunits of the OXPHOS complexes. Although evolutionarily related to bacterial ribosomes, mitochondrial ribosomes display some mechanistic and compositional differences from their prokaryotic counterparts. Mitochondrial ribosomes are entirely membrane-anchored, whereas in bacteria the ribosomes cycle between soluble and membrane-anchored populations. The mitochondrial ribosomes display a higher protein:rRNA content and this is largely attributed to (i) the presence of "mitospecific" extensions on many ribosomal proteins in addition to their bacterial homology domains, and (ii) the presence of novel mitochondrial-specific ribosomal proteins, i.e. that do not have bacterial counterparts. The role of the mitochondrial-specific ribosomal proteins/domains in ensuring that the assembly and activity of the ribosomes is tethered to the membrane is largely unexplored and represents a long-term goal of our research and focal point of our recently funded NSF grant application.

The Hig1 proteins and their association the cytochrome c oxidase complex (NIH funded)

We have recently identified two novel, and related, proteins with the yeast mitochondrial cytochrome bc1-cytochrome c oxidase (COX) supercomplex of the mitochondrial OXPHOS machinery, Rcf1 and Rcf2 (Strogolova et al., 2012). Yeast Rcf1/Rcf2 proteins are members of the highly conserved Hig1 (hypoxia induced gene 1, Hig1) protein family found in alphaproteobacteria and through to humans. The precise molecular function of the Hig1 protein and the identity of its partner proteins, are currently unknown. Due to the observed co-association of Rcf1 protein, the yeast Hig1 homolog, with the COX complex, we consider it possible that Rcf1 may function to regulate the affinity of the COX complex for oxygen. We have found that the yeast Rcf1 can associate with both the cytochrome bc1 and COX aspects of the supercomplex, suggesting it may represent a bridge between these two enzymes. The molecular characterization of the Rcf1/Hig1 proteins, both in yeast and in the nematode Caenorhabditis elegans is the focal point of our recently funded NIH R15 application. The function of the prokaryotic members of the Hig1 protein family is also being investigated using the nitrogen-fixing bacterium Rhizobium etli as a model system.


Selected Publications

Strogolova, V, Furness, A, Robb-McGrath, M., Garlich, J. and Stuart, R.A. 2012. Rcf1 and Rcf2,  members of the hypoxia-induced gene 1 protein family, are critical components of the mitochondrial cytochrome bc1-cytochrome c oxidase supercomplex. Mol. Cell. Biol., 32:1363-73.

Kaur, J., and Stuart, R.A.  2011.  Truncation of the Mrp20 protein reveals a novel ribosome assembly subcomplex in mitochondria. EMBO Reports, in press.

Stuart, R.A.  2009.  Supercomplex organization of the yeast respiratory chain complexes and the ADP/ATP carrier proteins. Methods Enzymol. 456: 191-208.

Stuart, R.A.  2009.  Supercomplex organization of the oxidative phosphorylation enzymes in yeast mitochondria. J. Bioenerg. Biomembr. 40: 411-417.

Jia, L., Kaur, J., and Stuart, R.A.  2009.  Mapping the yeast Oxa1-mitochondrial ribosome interface: identification of MrpL40, a ribosomal protein in close proximity to Oxa1 and critical for OXPHOS complex assembly. Eukaryot. Cell 11: 1792-1802.

Saddar, S., Dienhart, M.K., and Stuart, R.A.  2008.  The F1Fo-ATP synthase complex influences the assembly state of the cytochrome bc1-cytochrome oxidase supercomplex and its association with the TIM23 machinery. J. Biol. Chem. 283: 6677-6686.

Dienhart, M.K., and Stuart, R.A.  2008.  The yeast Aac2 protein exists in physical association with the cytochrome bc1-COX supercomplex and the TIM23 machinery. Mol. Biol. Cell. 19: 3934-3943.

 

Awards

Nora Finnigan Werra Faculty Achievement Award (2011)

Lawrence G. Haggerty Faculty Award for Research Excellence (2011)

Robert and Mary Gettel Faculty Award for Teaching Excellence (2008)

 

Current Lab Members

Joshua Garlich (Ph.D. student)

Vera Strogolova (Ph.D. student)

Jodie Box, Research Associate

Dr. Stuart is currently accepting new Ph.D. students into her lab

 

Former Students

Valerie Everard-Gigot, 2006, Ph.D.

Sonika Saddar, 2006, Ph.D

Lixia Jia, 2007, Ph.D.

Sherrea Herod, 2009, Ph.D.

Jeremy Bushman, 2005, B.S.

Andrew Furness, 2007, B.S.

Micaela Robb-McGrath, 2010, B.S.

Jasvinder Kaur, 2011, Ph.D.



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