Download MendeleyStructures of myxobacterial phytochrome revealed by cryo-EM using the Spotiton technique and with x-ray crystallography.
Karki, P., Menendez, D., Budell, W., Dangi, S., Hernandez, C., Mendez, J., Muniyappan, S., Basu, S., Schwander, P., Malla, T.N., Stojkovic, E.A., Schmidt, M.(2025) Struct Dyn 12: 034701-034701
- PubMed: 40322674
- DOI: https://doi.org/10.1063/4.0000301
- Primary Citation of Related Structures:
9NAA - PubMed Abstract:
Phytochromes are red-light photoreceptors first identified in plants, with homologs found in bacteria and fungi, that regulate a variety of critical physiological processes. They undergo a reversible photocycle between two distinct states: a red-light-absorbing Pr form and a far-red light-absorbing Pfr form. This Pr/Pfr photoconversion controls the activity of a C-terminal enzymatic domain, typically a histidine kinase (HK). However, the molecular mechanisms underlying light-induced regulation of HK activity in bacteria remain poorly understood, as only a few structures of unmodified bacterial phytochromes with HK activity are known. Recently, cryo-EM structures of a wild-type bacterial phytochrome with HK activity are solved that reveal homodimers in both the Pr and Pfr states, as well as a heterodimer with individual monomers in distinct Pr and Pfr states. Cryo-EM structures of a truncated version of the same phytochrome-lacking the HK domain-also show a homodimer in the Pfr state and a Pr/Pfr heterodimer. Here, we describe in detail how structural information is obtained from cryo-EM data on a full-length intact bacteriophytochrome, and how the cryo-EM structure can contribute to the understanding of the function of the phytochrome. In addition, we compare the cryo-EM structure to an unusual x-ray structure that is obtained from a fragmented full-length phytochrome crystallized in the Pr-state.
Organizational Affiliation:
Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, USA.
