INVESTIGADORES
VOJNOV Adrian Alberto
congresos y reuniones científicas
Título:
STRUCTURAL AND FUNCTION ANALYSES OF D199A MUTATION PROVIDE NEW INSIGHT INTO XCCBPHP BACTERIOPHYTOCHROME SIGNALING IN XANTHOMONAS CAMPESTRIS PV. CAMPESTRIS
Autor/es:
CONFORTE VP; HERNÁN R. BONOMI; JIMENA RINALDI; SEBASTIÁN KLINKE; FERNANDO A. GOLDBAUM; VOJNOV, ADRIAN ALBERTO; FLORENCIA SICILIANO
Reunión:
Congreso; SAIB; 2017
Resumen:
Many organisms possess photoreceptors that are capable of detectinglight wavelengths and transduce this information within cells.Phytochromes constitute a major superfamily of light-sensing proteinsthat are reversibly photoconverted between a red-absorbing(Pr) and a far-red-absorbing (Pfr) state. Xanthomonas campestrispv. campestris (Xcc), the causal agent of black rot disease, codesfor a functional bacteriophytochrome (XccBphP). Previous work ofour group have demonstrated that XccBphP is a bathyphytochromethat acts as a negative regulator of virulence. Here, we go deeplyinto the study of the XccBphP structure and function. In this work, weanalyze the role of the conserved residue Asp199 located in the photosensorydomain, which is crucial for photochemical Pr-to-Pfr conversion.For this aim, we purified the recombinant XccBphP-D199Afull-length mutant, crystalized it and solved the crystal structure,revealing a Pr state identical to the wild-type Pr structure. We alsoevaluated its UV-Vis absorption spectroscopic properties showingthat this mutation locks XccBphP in Pr state. Once the effect of themutation was established, we tested the effect of D199A during infection.We first complemented an XccbphP null mutant strain withXccBphP-D199A (D199A). We inoculated 10-day-old Arabidopsisplant seedlings with bacterial strains cultured under red, far-red ordark conditions. After 2 days p.i., bacterial CFU per plant mg weredetermined. We found that D199A was less virulent than the wildtypeand the XccbphP strains in all cases regardless of the lighttreatment. D199A ability to infect plants remained comparable tonull mutant strain carrying the plasmid with an intact XccbphP copy.Exopolysaccharide production, a known virulence factor, correlatedwith the infection results. Taken together, these results indicatethat D199A mutation locks XccBphP in an activated Pr-like state,irresponsive to light, inhibiting virulence factors and plant infectivity.