Orange Fluorescent Protein Research Articles

Directed evolution of a monomeric, bright and photostable version of Clavularia cyan fluorescent protein: structural characterization and applications in fluorescence imaging.

The arsenal of engineered variants of the GFP [green FP (fluorescent protein)] from Aequorea jellyfish provides researchers with a powerful set of tools for use in biochemical and cell biology research. The recent discovery of diverse FPs in Anthozoa coral species has provided protein engineers with an abundance of alternative progenitor FPs from which improved variants that complement or supersede existing Aequorea GFP variants could be derived. Here, we report the engineering of the first monomeric version of the tetrameric CFP (cyan FP) cFP484 from Clavularia coral. Starting from a designed synthetic gene library with mammalian codon preferences, we identified dimeric cFP484 variants with fluorescent brightness significantly greater than the wild-type protein. Following incorporation of dimer-breaking mutations and extensive directed evolution with selection for blue-shifted emission, high fluorescent brightness and photostability, we arrived at an optimized variant that we have named mTFP1 [monomeric TFP1 (teal FP 1)]. The new mTFP1 is one of the brightest and most photostable FPs reported to date. In addition, the fluorescence is insensitive to physiologically relevant pH changes and the fluorescence lifetime decay is best fitted as a single exponential. The 1.19 A crystal structure (1 A=0.1 nm) of mTFP1 confirms the monomeric structure and reveals an unusually distorted chromophore conformation. As we experimentally demonstrate, the high quantum yield of mTFP1 (0.85) makes it particularly suitable as a replacement for ECFP (enhanced CFP) or Cerulean as a FRET (fluorescence resonance energy transfer) donor to either a yellow or orange FP acceptor.

Bioluminescence imaging of vaccinia virus: Effects of interferon on viral replication and spread

Whole animal imaging allows viral replication and localization to be monitored in intact animals, which provides significant advantages for determining viral and host factors that determine pathogenesis. To investigate effects of interferons on spatial and temporal progression of vaccinia infection, we generated recombinant viruses that express firefly luciferase or a monomeric orange fluorescent protein. These viruses allow vaccinia infection to be monitored with bioluminescence or fluorescence imaging, respectively. The recombinant viruses were not attenuated in vitro or in vivo relative to a control WR virus. In cell culture, reporters could be detected readily by 4 h post-infection, showing that these viruses can be used as early markers of infection. The magnitude of firefly luciferase activity measured with bioluminescence imaging in vitro and in vivo correlated directly with increasing titers of vaccinia virus, validating imaging data as a marker of viral infection. Replication of vaccinia was significantly greater in mice lacking receptors for type I interferons (IFN I R −/−) compared with wild-type mice, although both genotypes of mice developed focal infections in lungs and brain after intranasal inoculation. IFN I R −/− mice had greater dissemination of virus to liver and spleen than wild-type animals even when mortality occurred at the same time point after infection. Protective effects of type I interferons were mediated primarily through parenchymal cells rather than hematopoietic cells as analyzed by bone marrow transplant experiments. Collectively, our data define a new function for type I interferon signaling in systemic dissemination of vaccinia and validate these reporter viruses for studies of pathogenesis.

Crystallization and preliminary crystallographic analysis of a novel orange fluorescent protein from the Cnidaria tube anemone Cerianthus sp.

A novel orange fluorescent protein, with excitation and emission maxima at 548 and 565 nm, respectively, from the Cnidaria tube anemone Cerianthus sp. has been cloned and overexpressed in Escherichia coli. The orange fluorescent protein has been crystallized by the sitting-drop vapour-diffusion method at 290 K using polyethylene glycol 3350 as a precipitant. A complete set of diffraction data was collected to 2.0 A resolution at 100 K. The crystals belong to the space group R3, with hexagonal unit-cell parameters a = b = 216.947, c = 51.839 A. There are four protein molecules in the asymmetric unit, giving a Matthews coefficient of 2.3 A(3) Da(-1) and a solvent content of 47%.

Cracks in the beta-can: fluorescent proteins from Anemonia sulcata (Anthozoa, Actinaria).

We characterize two green fluorescent proteins (GFPs), an orange fluorescent protein, and a nonfluorescent red protein isolated from the sea anemone Anemonia sulcata. The orange fluorescent protein and the red protein seem to represent two different states of the same protein. Furthermore, we describe the cloning of a GFP and a nonfluorescent red protein. Both proteins are homologous to the GFP from Aequorea victoria. The red protein is significantly smaller than other GFP homologues, and the formation of a closed GFP-like beta-can is not possible. Nevertheless, the primary structure of the red protein carries all features necessary for orange fluorescence. We discuss a type of beta-can that could be formed in a multimerization process.

Phytofluors: Phytochrome-Based Orange Fluorescent Protein Probes

Abstract Plants sense the light environment using pigment-protein complexes that discriminate light color, intensity, duration and direction. The most well-studied of these photoreceptors are the phytochromes, a family of soluble biliproteins found in plants, algae and cyanobacteria. Owing to the linear tetrapyrrole pigment phytochromobilin (PΦB) or phycocyanobilin (PCB) that is covalently linked to a large polypeptide via a thioether linkage, phytochromes perceive differences in the quality and quantity of light via their ability to photointerconvert between red (λmax660 nm) and far-red (λmax730 nm) light absorbing forms. Due to an efficient Z,E photoisomerization of the double bond between the C and D-ring pyrroles, phytochromes are nonfluorescent proteins with fluorescent quantum yields less than 10“3 at room temperature (Figure 1). Phytochrome genes have been cloned from a wide variety of photosynthetic organisms.