Alejandro P. Heuck

Associate Professor

We employ a variety of biophysical, biochemical, and molecular biological approaches to study protein structure, protein-membrane and protein-protein interactions.

Current Research

Engineering Bacterial Toxin to Measure Cholesterol Accessibility on Cell Membranes: Perfringolysin O (PFO) is a Cholesterol-dependent Cytolysin (CDC) secreted by Clostridium perfringens, the pathogenic bacteria that cause gas gangrene. PFO binds to cholesterol-containing membranes and oligomerizes to form large pores with diameters up to ~300 Å. The C-terminus of PFO (domain 4) mediates its initial binding to the membrane, and this binding trigger the structural rearrangements required to initiate the oligomerization of PFO monomers. Binding of PFO depends on the accessibility of cholesterol at the membrane surface. Cholesterol accessibility or the "ability" of cholesterol to interact with water-soluble molecules at the membrane surface, is modulated by the total cholesterol content and the composition of the membrane.

Most cholesterol sensors measure total cholesterol, however cholesterol accessibility can be altered by changes in the phospholipid composition of a membrane at a constant cholesterol concentration, like by action of phospholipases or sphingomyelinases. Our goal is to develop biosensors to detect and image changes on cholesterol accessibility on cell membranes.

Injection of Virulence Factors Through the Cell Membrane: Several pathogenic bacteria including Yersina ssp., Salmonella ssp., enterophatogenic E. coli, Pseudomonas aeruginosa, Shigella flexneri, etc., inject proteins directly into the eukaryotic cell cytoplasm to interfere with and to alter host processes. These proteins are presumably injected through the eukaryotic cell membrane via a proteinaceous transmembrane channel known as translocon, which is of bacterial origin. The translocons are thought to be transmembrane protein complexes consisting of several components. Our goal is to understand, at a molecular level, the assembly mechanism of the Type III secretion translocon into the target cell membrane

Academic Background

PhD University of Buenos Aires, Argentina
Postdoctoral training: Texas A&M University, College of Medicine

Selected Publications

Tang Y., Romano F.B., Brena M., and Heuck A.P. (2018) The Pseudomonas aeruginosa type III secretion translocator PopB assists the insertion of the PopD translocator into host cell membranes. J. Biol. Chem. 293, 8982-8993.

http://www.jbc.org/content/293/23/8982

Savinov S.N. and Heuck A.P. (2017) Interaction of cholesterol with Perfringolysin O: what have we learned from functional analysis? Toxins 7, 9, 381

http://www.mdpi.com/2072-6651/9/12/381

Johnson B.B., Breña M., Anguita J., and Heuck A.P. (2017) Mechanistic Insights into the Cholesterol-dependent Binding of Perfringolysin O-based Probes and Cell Membranes. Scientific Reports, 7, Article number: 13793

https://www.nature.com/articles/s41598-017-14002-x

Vermeulen A.J., Tang Y., Heuck A.P. (2016) Translocation of Toxins by Gram Negative Pathogens Using the Type III Secretion System. in Microbial Toxins, Toxinology. Springer, Dordrecht. Gopalakrishnakone, P., Alape-Girón, A., Stiles, B., Dubreuil, J.D., Mandal, M. (Eds.)

https://link.springer.com/referenceworkentry/10.1007/978-94-007-6725-6_29-1

Romano F.B., Tang Y., Rossi K.C., Monopoli K.R., Ross J.L., Heuck A.P. (2016) Type 3 Secretion translocators spontaneously assemble a hexadecameric transmembrane complex J. Biol. Chem. 291: 6304-6315.

Johnson B.B. and Heuck A.P. (2014) Perfringolysin O structure and mechanism of pore formation as a paradigm for cholesterol-dependent cytolysins. Subcell. Biochem. 80, 63-81.

Divakaruni AS, Wiley SE, Rogers GW, Andreyev AY, Petrosyan S, Loviscach M, Wall EA, Yadava N, Heuck AP, Ferrick DA, Henry RR, McDonald WG, Colca JR, Simon MI, Ciaraldi TP, Murphy AN. (2013) Thiazolidinediones are acute, specific inhibitors of the mitochondrial pyruvate carrier. Proc Natl Acad Sci U S A. 110, 5422-27.

Johnson B.B., Moe P.C., Wang Y.D., Rossi K., Trigatti B.L., and Heuck A.P. (2012) Modifications in Perfringolysin O domain 4 alter the threshold of cholesterol concentration required for binding. Biochemistry 51, 3373-3382

Romano F. B.,; Rossi, K.; Sava, C.G.; Holzenburg, A.; Clerico, E.M.; Heuck A. P. (2011) Efficient isolation of Pseudomonas aeruginosa type III secretion translocators and assembly of heteromeric transmembrane pores in model membranes. Biochemistry 50, 7117–7131.

Alejandro P. Heuck

Institute for Applied Life Sciences