Searching for proteins interacting with the Erp virulence factor from Mycobacterium tuberculosis by using the bacterial two-hybrid system

LAURA I KLEPP; MARÍA VERÓNICA BIANCO; FEDERICO C BLANCOA; MARÍA DE LA PAZ SANTANGELO; MARCELO SORIA; ANGEL CATALDI; FABIANA BIGI

BMC MOLECULAR BIOLOGY

BioMed Central Ltd

Año: 2009 p. 3 - 14

1471-2199

Background The exported repetitive protein (erp) gene encodes a secreted 36-kDa protein with a central domain containing several aminoacidic proline-glycine-leucine-threonine-serine (PGLTS) repeats. It has been demonstrated that Erp is a virulence-associated factor since the disruption of this gene impairs the growth of Mycobacterium bovis and Mycobacterium tuberculosis in mice. Results In order to elucidate the function of Erp we searched for Erp-binding proteins by screening an M. tuberculosis DNA library with full-length Erp using a bacterial two-hybrid system. Two different ORFs, whose products interact specifically with Erp, were identified. These are Rv1417 and Rv2617c and encode possible membrane proteins. Orthologues of Rv2617c are only disseminated in members of the M. tuberculosis complex (MTC), being absent in other Mycobacterium species. These preliminary protein-protein interaction results were confirmed by GST pull-down assays. The Erp domain involved in the interaction with Rv1417 and Rv2627c was mapped in the central and amino terminal domains of Erp. Erp members from Mycobacterium smegmatis and Mycobacterium leprae were not able to interact with Rv2617c in two-hybrid assays. The cellular topology of the putative Rv1417-Rv2617c-Erp complex was inferred by immunolocalization experiments of the three proteins in the bacterial cell. Finally, comparative genomics and expression studies revealed a possible role of Rv1417 in riboflavin metabolism. Conclusion We identified interactive partners of Erp, an M. tuberculosis protein involved in virulence, which will be the focus of future investigation to decipher the function of the Erp family protein.