1mzu
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Crystal Structure of the Photoactive Yellow Protein Domain from the Sensor Histidine Kinase Ppr from Rhodospirillum centenum
OverviewOverview
Photoactive yellow protein (E-PYP) is a blue light photoreceptor, implicated in a negative phototactic response in Ectothiorhodospira, halophila, that also serves as a model for the Per-Arnt-Sim superfamily of, signaling molecules. Because no biological signaling partner for E-PYP has, been identified, it has not been possible to correlate any of its, photocycle intermediates with a relevant signaling state. However, the PYP, domain (Ppr-PYP) from the sensor histidine kinase Ppr in Rhodospirillum, centenum, which regulates the catalytic activity of Ppr by blue light, absorption, may allow such issues to be addressed. Here we report the, crystal structure of Ppr-PYP at 2 A resolution. This domain has the same, absorption spectrum and similar photocycle kinetics as full length Ppr, but a blue-shifted absorbance and considerably slower photocycle than, E-PYP. Although the overall fold of Ppr-PYP resembles that of E-PYP, a, novel conformation of the beta 4-beta 5 loop results in inaccessibility of, Met-100, thought to catalyze chromophore reisomerization, to the, chromophore. This conformation also exposes a highly conserved molecular, surface that could interact with downstream signaling partners. Other, structural differences in the alpha 3-alpha 4 and beta 4-beta 5 loops are, consistent with these regions playing significant roles in the control of, photocycle dynamics and, by comparison to other sensory Per-Arnt-Sim, domains, in signal transduction. Because of its direct linkage to a, measurable biological output, Ppr-PYP serves as an excellent system for, understanding how changes in photocycle dynamics affect signaling by PYPs.
About this StructureAbout this Structure
1MZU is a Single protein structure of sequence from Rhodospirillum centenum with HC4 as ligand. Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of a photoactive yellow protein from a sensor histidine kinase: conformational variability and signal transduction., Rajagopal S, Moffat K, Proc Natl Acad Sci U S A. 2003 Feb 18;100(4):1649-54. Epub 2003 Jan 31. PMID:12563032
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