Crystal structure of a full-length bacteriophytochrome (Poster)

LISANDRO OTERO; JIMENA RINALDI; FERNANDO A. GOLDBAUM; SEBASTIÁN KLINKE; HERNÁN R. BONOMI

San Luis

Congreso; XII Reunión Anual de la Asociación Argentina de Cristalografía (AACr); 2016

Asociación Argentina de Cristalografía (AACr)

Phytochromes give riseto the largest photosensor family known to date. Plant, cyanobacterial, fungaland bacterial phytochromes share a canonical architecture consisting of anN-terminal photosensory module (PAS2-GAF-PHY domains) and a C-terminal variableoutput module. To date, severalphytochromes have been structurally characterized, but none of them include afull-length version. The bacterium Xanthomonascampestris pv. campestris, a worldwide agricultural pathogen, codes for asingle bacteriophytochrome (XccBphP)that has this canonical architecture, bearing a C-terminal PAS9 domain as theoutput module. Full-length XccBphP was cloned, expressed and purified tohomogeneity by nickel-NTA affinity and size-exclusion chromatography and wasthen crystallized at room temperature bound to its cofactor biliverdin. Acomplete native X-ray diffraction data set was collected to a maximumresolution of 3.25 A. The crystals belonged to space group P43212,with unit-cell parameters a = b = 103.94, c = 344.57 A. The structure was solved by molecular replacement showing a Prstate. The XccBphP quaternary assembly reveals ahead-to-head dimer in which the output module contributes to the helical dimerinterface. This work contributes to understand the light-induced structuralchanges propagated from the photosensor to the output modules in full-lengthphytochromes signaling.