Leonard H. Rome
Dr. Leonard Rome’s lab is using molecular engineering of a naturally occurring cellular structure called a vault to develop a flexible, targetable nano-scale capsule. Vaults are abundant cellular particles of unknown function found in nearly all eukaryotes (cells containing a nucleus). Cryo-electron microscopy combined with single particle reconstruction has provided overall dimensions of the vault at 42 x 75 nanometers (a nanometer is a millionth of a meter). These measurements indicate that the vault is larger in mass and size than many viruses. The overall structure of the intact vault is like a hollow barrel with two protruding caps and an indented waist with a very thin shell surrounding an internal cavity large enough to encompass several hundred proteins. Thus, the vault particle is a nanocapsule with incredible potential for compound encapsulation, protection, and delivery. Using a well-characterized insect virus into which a cloned gene can be easily inserted, it is possible to produce large quantities of a given protein in cultured insect cells.
The Rome lab has collaborated with a number of groups to use this system to produce large quantities of the major vault protein (MVP). The protein is able to self-assemble into vault-like particles. These MVP-only vaults are somewhat irregular, often containing distorted caps. However, lab members have demonstrated that co-production of all three vault proteins (MVP, TEP1 and VPARP) in insect cells results in self-assembly of particles that appear identical to naturally occurring vaults. By using molecular genetic techniques to modify the gene encoding the major vault protein, vault proteins have been produced with chemically active peptides attached to their sequence. These modified proteins are incorporated into the inside of the vault particle without altering its basic structure. The Rome lab proposes to produce modified vault particles in order to test the concept that vaults can be bioengineered to allow their use in a wide variety of biological applications including drug delivery, biological sensors, enzyme delivery, controlled release, and eventually as parts for nano-electrical machines.
Technical Research Interests
The members of the Rome lab are interested in the biogenesis and function of subcellular organelles. Resertachers have been concentrating on novel cytosolic ribonucleoprotein particles (RNPs) called vaults. Discovered in the Rome laboratory, vaults are found to exist in most eukaryotic cells. Vaults have an intricate shape composed of multiple arches reminiscent of cathedral vaults, hence their name. Vault size (~74 x 42 x42 nm), shape and localization; suggest that they may be involved in nucleo-cytoplasmic transport.
Researchers are interested in elucidating the function of these unique structures and in manipulating their structure to give them new functions. Members of the Rome lab are using the baculovirus expression system to produce recombinant vaults in order to test the concept that vaults can have a broad nanosystems application as malleable nanocapsules. Toward this aim they are currently designing particles with encapsulated fluorescent probes and enzymatically active protein domains. In addition, a number of strategies are currently being considered to encapsulate chemically active small molecules into the vault particle. If successful, these vault nanocapsules can be bioengineered to allow their use in a wide variety of biological applications including drug delivery, biological sensors, enzyme delivery, controlled release, and nano-electrical machine (NEMS) application.