Current Student Researchers
Supervisor: Ramchander Rohit Kongari
We are researching the spanin gp11 by amplifying its expression in gram-negative competent cells and extracting it from the cell membranes. We will then purify it and possibly denature it to learn more about the structure and function.
Supervisor: Jesse Cahill
Spanins are required for outer membrane disruption of Gram-negative hosts by phages. Therefore, the release of phage progeny is dependent on spanins. Rz and Rz1 of phage lambda are the best-studied spanins and recent evidence suggests spanins achieve the final step of lysis by fusion—fusing the inner and outer membrane of the host. A genetic screen identified single missense mutants of the spanin complex that block lysis. These mutations cluster in three regions of the complex, suggesting these regions are important for spanin function. However there were no single missense mutants identified in certain regions of the spanin complex, such as between two predicted alpha helices of Rz. Our hypothesis was that this region functions as a flexible linker, and has no other function (such as interaction or fusion). To test this hypothesis, we replaced a 15 aa stretch in this predicted linker region with Gly-Ser repeats. If specific residues were required in this region for spanin function, we would expect function to be lost. Surprisingly, the spanin complex functioned with an artificial linker replacing ~10% of the residues of this protein. My project will focus on extending and contracting this linker to probe the functional limits of the spanin complex. Additionally, I will be probing other regions of the spanin complex for regions that can tolerate linker substitution.
Supervisor: Karthik Chamakura
The single-stranded RNA phage M encodes a single 37 amino acid lysis protein, Mlys, with a predicted transmembrane domain and N-out, C-in topology. We propose to use both a genetic and a biochemical approach to determine its sub-cellular localization, mode of action for lysis, affected host factors, and key Mlys amino acid residues. Mlys is currently proposed to inhibit MraY, an enzyme that catalyzes the formation of the first lipid intermediate in cell wall biosynthesis, based on predicted similarities with the phiX174 phage lysis protein E; E is a transmembrane protein and exhibits an N-out, C-in topology as well. Many current antibiotics cause cell death by inhibiting penicillin-binding proteins (PBP), proteins that catalyze the polymerization and crosslinking of the glycan strands comprising peptidoglycan. However, long-term usage of such antibiotics has led to increased antibiotic resistance. Compounds causing cell death through other methods, then, have potential therapeutic value.
Supervisor: Jesse Cahill
The final component of phage lambda lysis of E. coli involves the spanins. The lambda spanins Rz and Rz1 disrupt the outer membrane (OM) creating a portal for release of phage progeny. Recent evidence suggests the spanins collapse the OM by fusing the two membranes of the cell envelope. It has been shown that Rz and Rz1 interact in the periplasm before lysis, however the exact sites of spanin interaction remain unknown. We aim to identify the interaction interfaces of Rz and Rz1 using biochemical and genetic approaches.
Supervisor: Karthik Chamakura
MS2 is a male-specific single-stranded RNA bacteriophage, which infects E. coli through the conjugative F pilus. The expression of the lysis protein, L, of this virus has been shown to induce random blebbing and eventual cell lysis although the exact mechanism is still unknown. Previous studies have documented this process after bacteria have grown in aerobic conditions, often in a water shaker bath. However, in nature, E. coli grow anaerobically and in a non-shaking environment – the intestinal tract. In order to more fully understand how L-induced lysis occurs in nature, we mimic these conditions by inducing L in E. coli growing anaerobically in a flow chamber under an optical microscope. Preliminary results show that blebs do not follow the formation and stabilization which is observed in aerobic conditions. The next step will be to repeat the procedure with other known proteins of single gene lysis systems and compare them to peptidoglycan-inhibiting antibiotics.
Supervisor: Adriana Hernandez-Morales
My 491 project this fall involves working with a protein that is produced by phage Petty. Gp38, which encodes an exopolysaccharide depolymerase, is a protein of interest due to its ability to degrade the biofilm surrounding the host bacteria, Acinetobacter baumanii. This protein is composed of three separate domains, one of which is believed to cause it to agglomerate in a fashion that keeps a detailed 3-D structure from being obtained. By making different forms of the functional protein that are devoid of that specific domain, it is hoped a more detailed 3-D structure can be obtained.
Former Student Researchers
|Johnson, Bryan||graduate school|
|Shrestha, Ritu||PhD program in Biology, Texas A&M University|
|Kaspar, Justin||PhD program in Interdisciplinary Biomedical Sciences at University of Florida|
|Lessor, Lauren||Research Assistant, CPT program, Texas A&M University|
|Mohan, Sheba||Physician Assistant, DFW|
|Tsau, Joshua||MD program, UT Houston Medical School|
|Dachowski, Michael||MD program, University of Texas Medical School, Houston|
|Herrera, Oscar||Clinical Pathology Laboratories, San Marcos|
|Lawler, Jessica||PhD, Dept. of Biological Chemistry & Molecular Pharmacology, Harvard Medical School|
|Migl, David||PhD program in Biophysics, Harvard University|
|Brahmbhatt, Kirtan||MD program, Texas A&M University Health Science Center|
|Kulkarni, Aneesha||PhD program in Molecular Biology focusing in immunology, San Jose State University|
|Park, Katherine||MD program, Baylor College of Medicine|
|Rasche, Eric||Programmer II , CPT program, Texas A&M University|
|Simpson, Jacob||MS Health Administration TAMU HSC|
|Edwards, Garrett||PhD program in Biochemistry, University of Colorado, Boulder|
|Khatemi, Brontee||the director of education at Sylvian Learning Center, Dallas, TX|
|Ladzekpo, Tsonyake||Medical Scribe at PhysAssist Scribes, Inc., Houston, TX|
|Luna, Adrian||PhD program in Biomedical Sciences, University of New Mexico|
|Snowden, Jeffrey||PhD program in Micro-logy & Cell Biology, University of Texas Medical Branch, Galveston|
|Church, Kaira||certification in Clinic Lab, UT Health Science Center in San Antonio, TX|
|Lancaster, Jacob||Research, Texas A&M University|
|Bernal, Christopher||Masters program in BIMS, Texas A&M|
|LeSage, Kayla||Masters program in BIMS, Texas A&M|
|Mijalis, Eleni||MD program at Louisiana State University – Shreveport|
|Crosby, Stephen||PhD program|
|Maughmer, Cory||Software Developer, CPT|