PT  - JOURNAL ARTICLE
AU  - Lisandro H. Otero
AU  - Sabrina Foscaldi
AU  - Giuliano T. Antelo
AU  - Serena Sirigu
AU  - Sebastián Klinke
AU  - Lucas A. Defelipe
AU  - Maximiliano Sánchez-Lamas
AU  - Giovanni Battocchio
AU  - Leonard M. G. Chavas
AU  - Fernando A. Goldbaum
AU  - Maria-Andrea Mroginski
AU  - Jimena Rinaldi
AU  - Hernán R. Bonomi
TI  - Structural basis for the Pr-Pfr long-range signaling mechanism of a full-length bacterial phytochrome at the atomic level
AID  - 10.1101/2021.02.16.430237
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.02.16.430237
4099  - http://biorxiv.org/content/early/2021/02/17/2021.02.16.430237.short
4100  - http://biorxiv.org/content/early/2021/02/17/2021.02.16.430237.full
AB  - Light sensing allows organisms to adapt to constantly changing environmental factors. Phytochromes constitute a widespread biological photoreceptor family that typically interconvert between two photostates called Pr (red light-absorbing) and Pfr (far-red light-absorbing). Despite the vast structural information reported on phytochromes, the lack of full-length structures at the (near-)atomic level in both pure Pr and Pfr states leaves gaps in the structural mechanisms involved in the signal transmission pathways during the photoconversion. Here we present three crystallographic structures from the plant pathogen Xanthomonas campestris virulence regulator bacteriophytochrome, including two full-length proteins, in the Pr and Pfr states. The structural findings, combined with mutational, biochemical and computational studies, allow us to describe the signaling mechanism of a full-length bacterial phytochrome at the atomic level, from the isomerization of the chromophore and the β-sheet/α-helix tongue transition to the remodeling of the quaternary assembly of the protein.TEASER Crystal structures of the full-length bacteriophytochrome XccBphP in both Pr and Pfr states unveil photoswitching mechanismCompeting Interest StatementThe authors have declared no competing interest.