The protein, called translation initiation factor 3, or IF3, is one of three proteins that make up the core structure of the machinery needed to guide the joining of messenger RNAs and ribosomes as protein translation commences. These three proteins have been widely considered to simply operate in a constitutive manner and play little, if any, role in regulating the expression of genes.
Fluorescence micrograph of a mutant of the filamentous cyanobacterium Fremyella diplosiphon showing the autofluorescence that results from the overaccumulation of the photosynthetic pigment phycoerythrin. This phenotype can result from the deletion of the gene encoding a translation initiation factor 3. | Photo by Xin Zhang and Lina Li
The new findings, from the laboratory of David M. Kehoe, professor of biology in the Indiana University Bloomington College of Arts and Sciences, reveals that IF3, in addition to its well-accepted function during translation initiation, also regulates the expression of genes that encode components of the photosynthetic machinery in response to changes in the color of light in the surrounding environment, a process known as “chromatic acclimation.”
These photosynthesis genes produce red-pigmented proteins called phycoerythrin in cyanobacteria when the cells are grown in green light and allow these organisms to efficiently absorb the predominant ambient light color for photosynthesis. The team uncovered the novel function of IF3 while searching for mutants that incorrectly regulated phycoerythrin. The discovery of this mutant was at first surprising, because in all other bacteria that have been examined, mutations in infC (the gene that encodes IF3) are lethal.
The team solved this puzzle by uncovering a second infC gene in Fremyella diplosiphon, the model organism for the study of light color responsiveness in cyanobacteria. While both IF3s, which have been named IF3a and IF3b, can act in the traditional role of translation initiation, only IF3a was found to also regulate photosynthetic gene expression.
By exploring the genomes of hundreds of prokaryotes and eukaryotes in collaboration with members of the laboratory of Indiana University Distinguished Professor and Class of 1955 Professor Jeffrey Palmer, the group identified a wide range of species whose genomes appear to have the potential to encode multiple IF3s, with one organism apparently encoding five distinct IF3 family members. And since almost none of these species are capable of chromatic acclimation, Kehoe believes that multiple IF3s must be used to regulate a wide range of environmental and perhaps developmental responses in both prokaryotes and eukaryotes.
“Particularly interesting was our finding that IF3 families exist in a number of plant species, including commercially important crops,” Kehoe said. “This means that new approaches to the modification of traits in agriculturally significant plant species may be possible by manipulating the expression patterns of different IF3 family members.”
The discovery has generated excitement for an additional reason. Historically, scientists have had a difficult time studying IF3 because it is so essential for translation initiation that it can not be altered without causing death. In fact, it remains one of the few proteins involved in translation for which no effective antibiotic has been developed. But the ability of the Kehoe team to delete either of the two infC genes in F. diplosiphon without causing lethality will allow the group to modify both IF3a and IF3b at will.
“Now that we know that F. diplosiphon contains two functionally different IF3s, and that each is nonessential, we have a unique opportunity to enhance our understanding of how the structural features of IF3 are related to its function,” Kehoe said. “Advancing our understanding of the role of IF3 in translation is likely to provide opportunities to develop new antibiotics that are targeted to this class of proteins.”
“A unique role for translation initiation factor 3 in the light color regulation of photosynthetic gene expression" is now available in early online editions of the Proceedings of the National Academy of Sciences. Co-authors with Kehoe and Palmer were Andrian Gutu, a former Ph.D. student in the Kehoe lab who is now a Howard Hughes Medical Institute Postdoctoral Fellow at Harvard University; April Nesbit, a former postdoctoral researcher in the Kehoe lab who is now a lecturer at Purdue Northwest; and Andrew Alverson, a former postdoctoral fellow in the Palmer lab who is now a faculty member at the University of Arkansas. Primary funding for the work was provided by the National Science Foundation, with support provided to Nesbit by the National Institutes of Health.
Stephen Chaplin | EurekAlert!
New data unearths pesticide peril in beehives
21.04.2017 | Cornell University
New rice fights off drought
04.04.2017 | RIKEN
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
25.04.2017 | Physics and Astronomy
25.04.2017 | Materials Sciences
25.04.2017 | Life Sciences