Center Profile

MPID

MPID: Advancing Technologies to Facilitate Study of Infectious Disease-Related Membrane Proteins

MPIDAs the Ebola epidemic in Africa worsens, the challenges associated with developing therapeutics to combat infectious disease become more obvious. Part of the difficulty lies in understanding the workings of sometimes recalcitrant membrane proteins. These biomolecules are involved in both sides of the infectious process: pathogen membrane proteins and human Petra Fromme membrane proteins that interact with the pathogens. Understanding these host-pathogen interactions at an atomic level is critical for unraveling the molecular mechanisms of pathogenesis. One of the major objectives of the Center for Membrane Proteins in Infectious Diseases (MPID), a Protein Structure Initiative (PSI) Center for Membrane Protein Structure Determination, is to determine the structure, dynamics, and function of membrane proteins, thereby providing insight into the role of these biomolecules in infectious disease pathways. Principal Investigator (PI) Petra Fromme (pictured right), Professor of Chemistry & Biochemistry at Arizona State University (ASU), has built an inter-disciplinary team of Co-PIs to attack the challenges of membrane protein expression, crystallization, structure determination, and more, within the context of viral and bacterial pathogenesis.

MPID is committed to speeding up this process by developing new technologies to increase the throughput of protein structure determination. Last year, MPID researchers made an advance in the area of protein expression. Led by Co-PI Tsafrir Mor, Associate Professor of Biomedicine & Biotechnology at ASU, scientists expressed HIV enveloped virus-like particles (VLPs) in Nicotiana benthamiana plants by stable transformation (Kessans, et al., 2013). The particles consisted of the HIV structural protein, Gag, and a deconstructed form of HIV-1 gp41, important for viral mucosal transmission and infection. Gag is a desirable target, as it has been suggested as a target of cellular immunity that may control viral load. This work provides further support for a broadly effective and inexpensive HIV-1 vaccine.

In the realm of protein crystallization, Co-PI Martin Caffrey, Professor of Membrane Structural and Functional Biology at Trinity College Dublin, and his team developed a system based on commercially available robots to dispense lipidic mesophases (Cherezov, et al., 2004; basic schematic from the Cherezov Lab website). in meso robot One of the challenges associated with using mesophases as a hosting agent for crystallizing proteins is that it is extremely sticky and viscous, similar to toothpaste, and therefore difficult to dispense in small volumes quickly and consistently. Three commercially available robots can dispense the mesophase with speed, precision, and accuracy, thereby facilitating the crystallization process and decreasing the overall time needed for structure determination (Li, et al., 2012).

Fromme is a pioneer in the use of free electron lasers in structural biology and a member of BioXFEL, the NSF Science and Technology Center for Biology with X-ray Free Electron Lasers. By drawing on Fromme’s experience with XFEL, MPID can play a crucial role in advancing this area of membrane protein structure determination. Structures that have been solved by MPID researchers using serial femtosecond x-ray crystallography technology include a photosynthetic reaction center from Blastochloris viridis (4CAS; thumbnail image) and a human serotonin receptor (4NC3). This work lays the groundwork for the application of this technology to solve the structures of proteins integral to pathogenicity. Combined with the efforts of the other researchers in this Center, and in collaboration with scientists in the community, significant advances can be made in the area of bacterial and viral infectious disease.


Read more about the use of free electron lasers in structural biology in
the current Featured Technology article,
Delivering on the Promise of Free Electron Lasers.


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