Download We are studying RipA, RipB and RipC in Yersinia pestis as

Structural Characterization of RipA, RipB and RipC from Yesinia Pestis
Rodrigo Torres
Mentor: Celia Goulding
We are studying RipA, RipB and RipC in Yersinia pestis as a model system as the proteins
responsible for Mycobacterium tuberculosis (Mtb) replication in postactivated macrophages and
Mtb viability. In a recent study, RipA, RipB and RipC have been found to be necessary for Y.
pestis replication in postactivated macrophages. RipC in Y. pestis is a homolog of Mtb CitE,
which is the beta subunit of citrate lyase, a three-subunit protein complex that converts citrate to
acetyl-CoA and oxaloacetate. Both Mtb and Y. pestis genomes only contain the gene that
encodes for CitE, but not the genes that encode alpha and gamma subunits of citrate lyase, which
suggests that Mtb and Y. pestis CitE function differently from CitE in the citrate lyase complex.
Interestingly, within the Mtb and Y. pestis genomes, the genes surrounding citE are similar,
inferring that the proteins encoded within both operons have similar functions. Mtb also lives in
macrophages, and hence the homologous Mtb proteins to RipA, RipB and RipC are implicated in
replication in postactivated macrophages. Therefore, structure determination of Y. pestis RipA,
RipB and RipC will shed light on the function and may be useful in structure-based anti-TB drug
design. RipC has been purified and has been crystallized in 30% ethylene glycol. By x-ray
crystallography, we have shown that the RipC crystals diffract and have collected a medium
resolution dataset. Currently, we are in the process of solving the 3-D x-ray crystal structure.