Photostate-Stabilizing Mutants of the Bacteriophytochrome from the Plant Pathogen study of XANTHOMONAS CAMPESTRIS

ANTELO GT; KLINKE S; SÁNCHEZ-LAMAS M; CONFORTE VP; MALAMUD F; GOLDBAUM FA; OTERO L; BONOMI HR; RINALDI JIMENA

Paraná

Congreso; SAIB; 2018

Bacteriophytochromes (BphPs) are part of the phytochrome superfamily of photoreceptors. BphPs are proteins that bind biliverdin (BV) as theirchromophore and typically present two photostates: a primarily red-absorbing form (Pr) and a far-red-absorbing form (Pfr). See fig 1.We have recently shown that the BphP from the plant pathogen bacterium Xanthomonas campestris (XccBphP) modulates the interaction with itshost1, and performed several biophysical studies showing that XccBphP is a bathy-like phytochrome (Pfr-enriched equilibrium as ground-state).Moreover, we have resolved the 3D crystal structure of the full-length protein in the Pr state (a first in photobiology, fig 2)2.In order to evaluate the biological role of XccBphP in vivo and resolve its structure in the Pfr state , we have designed point and randomized mutantsof XccBphP in conserved residues linked to the photochemical behavior. These were studied by means of a UV-VIS spectroscopy protocol designedfor a rapid and precise characterization of mutants (fig 3). Here we show our results obtained so far.