Structural basis for iron (II) metabolism in encapsulated ferritin-like proteins

Ferritins are ubiquitous proteins that serve the dual-function of iron reservoir and sequestering the Fe(II) toxicity. The function of ferritins totally depends on the characteristic spherical structure with a di-iron centre performing the iron oxidation and a hallow cavity enclosing the iron minerals in a bioavailable form. I have characterised the structure, assembly and function of a new member of ferritin superfamily that is natively enclosed within an encapsulin shell. Encapsulin proteins are structurally-related to a virus capsid and form 60-meric or 180-meric icosahedrons. I show that this encapsulin associated ferritin-like protein (EncFtn) possesses two main alpha helices, which assemble in a metal-dependent manner to form a ferroxidase centre at a dimer interface. EncFtn adopts an annular decamer structure in contrast to the 24-meric classical ferritins or 12-meric mini-ferritin (DPS). The resemblance of the dimeric EncFtn and monomeric classical ferritins suggests that it is likely that classical ferritin evolves from EncFtn because of the gene duplication. EncFtn is a catalytically active ferroxidase but with only a limited iron binding ability due to its open structure. The encapsulin itself is not able to oxidise Fe(II), but is able to store about 2200 iron ions. I have demonstrated that the EncFtn must be housed in the encapsulin to achieve a maximum loading of approximately 4200 iron ions. The encapsulin nanocompartments are widely-distributed in both eubacteria and archaeon with distinct life styles and represent a distinct class of iron storage system, where iron oxidation and mineralisation are distributed between two proteins

Non-Contact Detection of Vital Signs Based on Improved Adaptive EEMD Algorithm (July 2022)

Non-contact vital sign detection technology has brought a more comfortable experience to the detection process of human respiratory and heartbeat signals. Ensemble empirical mode decomposition (EEMD) is a noise-assisted adaptive data analysis method which can be used to decompose the echo data of frequency modulated continuous wave (FMCW) radar and extract the heartbeat and respiratory signals. The key of EEMD is to add Gaussian white noise into the signal to overcome the mode aliasing problem caused by original empirical mode decomposition (EMD). Based on the characteristics of clutter and noise distribution in public places, this paper proposed a static clutter filtering method for eliminating ambient clutter and an improved EEMD method based on stable alpha noise distribution. The symmetrical alpha stable distribution is used to replace Gaussian distribution, and the improved EEMD is used for the separation of respiratory and heartbeat signals. The experimental results show that the static clutter filtering technology can effectively filter the surrounding static clutter and highlight the periodic moving targets. Within the detection range of 0.5 m similar to 2.5 m, the improved EEMD method can better distinguish the heartbeat, respiration, and their harmonics, and accurately estimate the heart rate

Conservation of the structural and functional architecture of encapsulated ferritins in bacteria and archaea

Ferritins are a large family of intracellular proteins that protect the cell from oxidative stress by catalytically converting Fe(II) into less toxic Fe(III) and storing iron minerals within their core. Encapsulated ferritins (EncFtn) are a sub-family of ferritin-like proteins, which are widely distributed in all bacterial and archaeal phyla. The recently characterized Rhodospirillum rubrum EncFtn displays an unusual structure when compared with classical ferritins, with an open decameric structure that is enzymatically active, but unable to store iron. This EncFtn must be associated with an encapsulin nanocage in order to act as an iron store. Given the wide distribution of the EncFtn family in organisms with diverse environmental niches, a question arises as to whether this unusual structure is conserved across the family. Here, we characterize EncFtn proteins from the halophile Haliangium ochraceum and the thermophile Pyrococcus furiosus, which show the conserved annular pentamer of dimers topology. Key structural differences are apparent between the homologues, particularly in the centre of the ring and the secondary metal-binding site, which is not conserved across the homologues. Solution and native mass spectrometry analyses highlight that the stability of the protein quaternary structure differs between EncFtn proteins from different species. The ferroxidase activity of EncFtn proteins was confirmed, and we show that while the quaternary structure around the ferroxidase centre is distinct from classical ferritins, the ferroxidase activity is still inhibited by Zn(II). Our results highlight the common structural organization and activity of EncFtn proteins, despite diverse host environments and contexts within encapsulins

Ferritin family proteins and their use in bionanotechnology

Ferritin family proteins are found in all kingdoms of life and act to store iron within a protein cage and to protect the cell from oxidative damage caused by the Fenton reaction. The structural and biochemical features of the ferritins have been widely exploited in bionanotechnology applications: from the production of metal nanoparticles; as templates for semi-conductor production; and as scaffolds for vaccine design and drug delivery. In this review we first discuss the structural properties of the main ferritin family proteins, and describe how their organisation specifies their functions. Second, we describe materials science applications of ferritins that rely on their ability to sequester metal within their cavities. Finally, we explore the use of ferritin as a container for drug delivery and as a scaffold for the production of vaccines

Single crystal X-ray diffraction data for Hoch_3836 (1-98)

<p>Single crystal X-ray diffraction data for Hoch_3836 (1-987) related to PDBID: 5N5F</p> <p>Data collected at Diamond Light Source, UK.</p

How does an encapsulated ferritin-like protein store iron?

Poster for British Biophysical Society 2016 Biennial Meeting

Single crystal X-ray diffraction data for PFC_05175 (1-99)

<p>Single crystal X-ray diffraction data for PFC_05175 (1-99) related to PDBID: 5N5E</p> <p>Data collected at Diamond Light Source, UK</p

Single crystal X-ray diffraction data for Rhodospirillum rubrum encapsulated ferritin Rru_A0973, short His-tagged variant

Single crystal X-ray diffraction images taken for crystals of Ru_A0973 short-His variant. Related to PDBID: 5DA5He, Didi; Marles-Wright, Jon; Georgiev, Atanas. (2016). Single crystal X-ray diffraction data for Rhodospirillum rubrum encapsulated ferritin Rru_A0973, short His-tagged variant, [dataset]. University of Edinburgh. School of Biological Sciences. http://dx.doi.org/10.7488/ds/134