Weitz Group @ Georgia Tech

Theoretical Ecology and Quantitative Biology

2013

Monday, January 28, 2013 - 22:43
Death at a nanometer scale - how lytic enzymes explode cells from the outside

The rise of antibiotic-resistant bacteria has initiated a quest for alternatives to conventional antibiotics. One potential alternative is PlyC, a potent enzyme that kills the bacteria that causes strep throat and streptococcal toxic shock syndrome. PlyC operates by locking onto the surface of a bacteria cell and chewing a hole in the cell wall large enough for the bacteria's inner membrane to protrude from the cell, ultimately causing the cell to burst and die.

Tesearch has shown that alternative antimicrobials such as PlyC can effectively kill bacteria. However, fundamental questions remain about how bacteria respond to the holes that these therapeutics make in their cell wall and what size holes bacteria can withstand before breaking apart. Answering those questions could improve the effectiveness of current antibacterial drugs and initiate the development of new ones.

Researchers at the Georgia Institute of Technology (Gabriel Mitchell, Prof. Kurt Wiesenfeld, and Prof. Joshua Weitz) and the University of Maryland (Prof. Daniel Nelson) recently conducted a study to try to answer those questions. The researchers created a biophysical model of the response of a Gram-positive bacterium to the formation of a hole in its cell wall. Then they used experimental measurements to validate the theory, which predicted that a hole in the bacteria cell wall larger than 15 to 24 nanometers in diameter would cause the cell to lyse, or burst. These small holes are approximately one-hundredth the diameter of a typical bacterial cell.

More information in the article available online at the Journal of the Royal Society Interface

2012

Wednesday, February 1, 2012 - 10:32
How new viruses evolve key innovations

Joshua Weitz is a member of a research team led by Michigan State researchers Justin Meyer and Richard Lenski who published an article detailing how viruses evolve key innovations. The original article can be found on the Science homepage. More coverage can be found here:

2011

Thursday, January 13, 2011 - 15:15
Improving Plants: New Software Tool Quantifies the Complex Structure of Leaf Venation Networks, Enabling Advances in Plant Biology

The Weitz group has recently published a "Breakthrough Technology" article based on user-assisted software to analyze the structure of leaf venation networks. The program, called Leaf Extraction and Analysis Framework Graphical User Interface (LEAF GUI), enables scientists and breeders to measure the properties of thousands of veins much more quickly than manual image analysis tools.

More details concerning press coverage can be found here:

2010

Tuesday, November 2, 2010 - 20:12
Undergraduate Team of Synthetic Biology Engineers Head for First Competition

Prof. Weitz and Richard Joh are two of the co-instructors for the first ever Georgia Tech International Genetically Engineered Machine (iGEM) team, along with Prof. Eric Gaucher and Prof. Mark Styczynski. Initiated in January 2003, the iGEM competition is considered the premiere undergraduate synthetic biology competition. Since spring 2010, the team of 13 undergraduates has focused on a project designed to synthetically engineer heat-producing bacterial cells in response to exposure to cold environments.

More info about the team can be found here:

Monday, October 4, 2010 - 12:02
Characterizing enzymes to explode superbugs

Gabriel Mitchell and Joshua Weitz -- from our group here at the Georgia Institute of Technology -- collaborated with Daniel Nelson, a biochemist specializing in phage lytic enzymes at the University of Maryland, in a collaborative project to develop a novel assay to quantify how a new class of enzybiotics can explode bacterial pathogens. The results are available online on Physical Biology.

Discussion of this work can be found online:

2008

Tuesday, September 30, 2008 - 23:00
Collective fate determination in bacterial viruses

For many bacterial viruses, the choice of whether to kill host cells or enter a latent state depends on the multiplicity of coinfection. We recently suggested a nonlinear basis for the finding that deterministic decisions can be reached, e.g., lysis or latency, depending on the cellular multiplicity of infection. The results were published in Biophysical Journal, Collective decision making in bacterial viruses.

Discussion of our findings can be found online:

Sunday, August 31, 2008 - 23:00
Research Horizons Profile of Systems Biology at Georgia Tech

Joshua Weitz, former postdoc Dr. Yuriy Mileyko and graduate student Richard Joh were profiled as part of an article on Systems Biology at Georgia Tech.