Structural rearrangement in the Xanthomonas campestris bacteriophytochrome during photoconversion

RINALDI, JIMENA; GOLDBAUM, FERNANDO A.; ANTELO, GIULIANO; BONOMI, HERNAN R.; KLINKE, SEBASTIÁN; SANCHEZ-LAMAS, MAXIMILIANO; OTERO, LISANDRO H.

Valparaíso

Congreso; III Reunión de Asociación Latinoamericana de Cristalografía y Primer Encuentro de la Asociación Chilena de Cristalografía (AChCr); 2018

Asociación Latinoamericana de Cristalografía y Asociación Chilena de Cristalografía

The phytopathogenicbacterium Xanthomonas campestris codes for a singlebacteriophytochrome photoreceptor(XccBphP) that bears a photosensory module (PAS2-GAF-PHY domains) anda C-terminal PAS9 outputmodule. This microorganism is able to regulate its virulence bysensing red and far-red light through XccBphP [1]. We havecrystallized [2] and determined the structure [3] of the dimericfull-length XccBphP in its red-absorbing state (Pr) at 3.25 Åresolution. Very recently, we have also solved the structures of thephotosensory module alone (ΔPAS9) in its far red-absorbing state(Pfr) at 2.90 Å resolution and the full-length Pfr-stabilizedXccBphP G454E mutant at 2.50 Å resolution. In this work, we describethe main properties of the different variants obtained and thebiophysical and biochemical aspects that govern the activation andinterconversion of the Pr and Pfr forms of the protein. This work providesnew insights in the understanding of the molecular mechanisms behindphytochrome signaling in bacteria and its role in infection, and mayserve as a model for the orthologous phytochromes present in plants.