Daniel E. Goldberg, M.D., Ph.D.

Professor
Internal Medicine
Infectious Diseases
Molecular Microbiology

Molecular Microbiology and Microbial Pathogenesis Program
Biochemistry, Biophysics, and Structural Biology Program
Molecular Cell Biology Program

Research Abstract:

Parasites have evolved many clever ways to infect their hosts and develop within them. Study of these processes at a molecular level should lead to treatment or prevention of parasitic infections that afflict most of humanity. It will also shed light on general principles of biochemistry and cell biology. The organism we are studying is Plasmodium falciparum, a protozoan parasite that causes malaria.
Most of the malaria parasite`s adaptations to intracellular survival are still biological mysteries. Indeed, nearly half of the Plasmodium proteome comprises proteins of unknown function. Some are species or phylum specific; others have orthologs spread widely through phylogeny. We are interested in defining the roles of such proteins, with a special focus on proteases of unknown function. We use a combination of genetic and biochemical approaches to elucidate biological roles. To help us with this analysis, we have developed a regulated protein knockdown system for the study of essential proteins. This has allowed us to define a role for Plasmodium calpain in nucleolar control of cell cycle progression and a role for the aspartic protease plasmepsin V in export of parasite proteins to the host erythrocyte.
We are particularly interested in exported proteins. The parasite exports several hundred proteins into its host erythrocyte. What are these proteins doing in the host cell and beyond? How do the proteins get out of the parasite?
Another mysterious attribute of the Plasmodium proteome is that nearly one-third of all proteins have runs of asparagine. Two proteins we are studying have 30 and 80 consecutive asparagines. What are these asparagines for? Since polyasparagine is amyloidogenic, how does the cell handle all these proteins? Using genetic and biochemical manipulations, we are trying to address such issues.
Plasmodium has more than 5,000 predicted gene products. New drug targets are desperately needed, but which genes are essential? We are using approaches such as allelic replacement and chemical genetics to get at this question. One focus is isoleucine utilization. We have found that isoleucine is the sole exogenous amino acid required for parasite growth. By selecting parasites resistant to isoleucine utilization inhibitors, we have been able to define targets within this pathway. Whole genome sequencing can pinpoint resistance mutations. Allelic replacement then allows us to show that a given mutation in a target is responsible for the observed resistance.
Our work involves a combination of biochemical, genetic, genomic, cell biological, and physiological approaches aimed at understanding the biology of this nefarious organism.

Selected Publications:

*Istvan ES, Mallari J, Corey V, Dharia N, Marshall G, Winzeler EA, Goldberg DE: Esterase mutation is a mechanism of resistance to antimalarial compounds. Nature Commun 2017, in press.

*Pal P, Daniels B, Oksman A, Diamond M, Klein RS, Goldberg DE: Plasmodium falciparum histidine-rich protein II compromises brain endothelial barriers and may promote cerebral malaria pathogenesis; mBio 2016, 7: e00817-16.

*Sigala PA, Crowley JR, Henderson JP, Goldberg DE: Deconvoluting heme biosynthesis to target blood-stage malaria parasites. eLife 2015, 4: e09143.

*Spillman N, Beck J, Goldberg D: Protein export into malaria parasite-infected erythrocytes: mechanisms and functional consequences; Ann Rev Biochem 2015; 84: 813-841.

*Beck J, Muralidharan V, Oksman A, Goldberg DE: PTEX component HSP101 mediates export of diverse malaria effectors into host erythrocytes; Nature 2014, 511: 592-595.

*Sigala PA, Goldberg DE: Heme metabolism in Plasmodium; Ann Rev Microbiol 2014; 68: 259-278.

*Ledbetter S, Altenhofen L, Cobbold SA, Istvan ES, Fennell C, Doerig C, Llinas M, Goldberg DE: Plasmodium falciparum responds to amino acid starvation response by entering into a hibernatory state; Proc Natl Acad Sci USA 2012, 109: E3278-E3287. PMC3511138.

*Muralidharan V, Oksman A, Goldberg DE: Heat shock protein 110 maintains the asparagine-rich proteome of Plasmodium falciparum; Nature Comm 2012, 3: 1310. PMC3639100.

*Muralidharan V, Oksman A, Iwamoto M, Wandless TJ, Goldberg DE: Asparagine repeat function in a Plasmodium falciparum protein assessed with a regulatable fluorescence affinity tag; Proc Natl Acad Sci USA 2011, 108: 4411-4416. PMC3060247.

*Istvan ES, Dharia NV, Gluzman I, Winzeler EA, Goldberg DE: Validation of isoleucine utilization targets in Plasmodium falciparum; Proc Natl Acad Sci USA 2011, 108: 1627-1632. PMC3029723.

*Russo I, Babbitt S, Muralidharan V, Butler T, Oksman A, Goldberg DE: Plasmepsin V licenses Plasmodium proteins for export into the host erythrocyte; Nature 2010, 463: 632-636. PMC2826791.

Last Updated: 1/13/2017 7:52:57 AM

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