heme binding
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2021 ◽  
Vol 118 (50) ◽  
pp. e2114347118
Author(s):  
Tengzhao Song ◽  
Yiyuan Shi ◽  
Like Shen ◽  
Chengjuan Cao ◽  
Yue Shen ◽  
...  

Potassium (K+) is an essential element for growth and development in both animals and plants, while high levels of environmental sodium (Na+) represent a threat to most plants. The uptake of K+ from high-saline environments is an essential mechanism to maintain intracellular K+/Na+ homeostasis, which can help reduce toxicity caused by Na+ accumulation, thereby improving the salt tolerance of plants. However, the mechanisms and regulation of K+-uptake during salt stress remain poorly understood. In this study, we identified an endoplasmic reticulum–localized cytochrome b5 (OsCYB5-2) that interacted with a high-affinity K+ transporter (OsHAK21) at the plasma membrane. The association of OsCYB5-2 with the OsHAK21 transporter caused an increase in transporter activity by enhancing the apparent affinity for K+-binding but not Na+-binding. Heme binding to OsCYB5-2 was essential for the regulation of OsHAK21. High salinity directly triggered the OsHAK21–OsCYB5-2 interaction, promoting OsHAK21-mediated K+-uptake and restricting Na+ entry into cells; this maintained intracellular K+/Na+ homeostasis in rice cells. Finally, overexpression of OsCYB5-2 increased OsHAK21-mediated K+ transport and improved salt tolerance in rice seedlings. This study revealed a posttranslational regulatory mechanism for HAK transporter activity mediated by a cytochrome b5 and highlighted the coordinated action of two proteins to perceive Na+ in response to salt stress.


2021 ◽  
Vol 448 ◽  
pp. 214189
Author(s):  
Brian J. Goodfellow ◽  
Filipe Freire ◽  
Ana Luísa Carvalho ◽  
Susana S. Aveiro ◽  
Peggy Charbonnier ◽  
...  

2021 ◽  
Author(s):  
Sarah Teakel ◽  
Michealla Marama ◽  
David Aragão ◽  
Sofiya Tsimbalyuk ◽  
Jade K. Forwood ◽  
...  

We recently reported that the membrane associated progesterone receptor (MAPR) protein family (mammalian members: PGRMC1, PGRMC2, NEUFC and NENF) originated from a new class of prokaryotic cytochrome b5 (cytb5) domain proteins, called cytb5M (MAPR-like). Relative to classical cytb5 proteins, MAPR and ctyb5M proteins shared unique sequence elements and a distinct heme binding orientation at an approximately 90⁰ rotation relative to classical cytb5, as demonstrated in the archetypal crystal structure of a cytb5M protein (PDB accession number 6NZX). Here, we present the second crystal structure of an archaeal cytb5M domain (Methanococcoides burtonii WP_011499504.1, PDB:6VZ6). It exhibits similar heme-binding to the 6NZX cytb5M, supporting the deduction that MAPR-like heme orientation was inherited from the prokaryotic ancestor of the original eukaryotic MAPR gene.


2021 ◽  
Author(s):  
Daniel Tamarit ◽  
Sarah Teakel ◽  
Michealla Marama ◽  
David Aragão ◽  
Svetlana Y. Gerdes ◽  
...  

The multiple functions of PGRMC1, the archetypal heme-binding eukaryotic MAPR family member, include steroidogenic regulation, membrane trafficking, and steroid responsiveness. The interrelationships between these functions are currently poorly understood. Previous work has shown that different MAPR subclasses were present early in eukaryotic evolution, and that tyrosine phosphorylated residues appeared in the eumetazoan ancestor, coincident with a gastrulation organizer. Here we show that MAPR proteins are related to a newly recognized class of prokaryotic cytochrome-b5 domain proteins. Our first solved structure of this new class exhibits shared MAPR-like folded architecture and heme-binding orientation. We also report that a protein subgroup from Candidate Phyla Radiation (CPR) bacteria shares MAPR-like heme-interacting tyrosines. Our results support bacterial origins for both PGRMC1 and CYP51A, that catalyze the meiosis-associated 14-demethylation of the first sterol lanosterol from yeast to humans. We propose that eukaryotic acquisition of a membrane-trafficking function related to sterol metabolism was associated with the appearance of MAPR genes early in eukaryotic evolution.


FEBS Journal ◽  
2021 ◽  
Author(s):  
Shiyou Che ◽  
Yakun Liang ◽  
Yujing Chen ◽  
Wenyue Wu ◽  
Ruihua Liu ◽  
...  

Author(s):  
Vasiliki‐Dimitra C. Tsolaki ◽  
Sofia K. Georgiou‐Siafis ◽  
Athina I. Tsamadou ◽  
Stefanos A. Tsiftsoglou ◽  
Martina Samiotaki ◽  
...  

2021 ◽  
Author(s):  
Hannah L. Raczkowski ◽  
Li S. Xu ◽  
Wei Cen Wang ◽  
Rodney P DeKoter

Spi-C is an E26 transformation-specific transcription factor closely related to PU.1 and Spi-B. Spi-C has lineage-instructive functions important in antibody-generating responses, B cell development, and red pulp macrophage generation. Spi-C is inducible by heme- and NF-κB-dependent pathways in macrophages. The present research aimed to examine the regulation of Spi-C expression in B cells. RT-qPCR analysis revealed that Spic expression was reduced in B cells following addition of lipopolysaccharide, anti-IgM antibodies, CD40L, or cytokines BAFF + IL-4 + IL-5. Cytochalasin treatment partially prevented downregulation of Spic. Unstimulated B cells upregulated Spic over time in culture. To determine the mechanism of Spic regulation, we examined the Spic promoter and upstream regulatory elements. The Spic promoter had unidirectional activity, which was reduced by mutation of an NF-κB binding site. Spic was repressed by an upstream regulatory region interacting with the heme-binding regulator Bach2. Taken together, these data indicate that Spi-C is dynamically regulated by external signals in B cells and provide insight into the mechanism of regulation.


2021 ◽  
Vol 9 (7) ◽  
pp. 1455
Author(s):  
Fei Yu ◽  
Xinrui Zhao ◽  
Ziwei Wang ◽  
Luyao Liu ◽  
Lingfeng Yi ◽  
...  

Vitreoscilla hemoglobin (VHb), the first discovered bacterial hemoglobin, is a soluble heme-binding protein with a faster rate of oxygen dissociation. Since it can enhance cell growth, product synthesis and stress tolerance, VHb has been widely applied in the field of metabolic engineering for microorganisms, plants, and animals. Especially under oxygen-limited conditions, VHb can interact with terminal oxidase to deliver enough oxygen to achieve high-cell-density fermentation. In recent years, with the development of bioinformatics and synthetic biology, several novel physicochemical properties and metabolic regulatory effects of VHb have been discovered and numerous strategies have been utilized to enhance the expression level of VHb in various hosts, which greatly promotes its applications in biotechnology. Thus, in this review, the new information regarding structure, function and expressional tactics for VHb is summarized to understand its latest applications and pave a new way for the future improvement of biosynthesis for other products.


2021 ◽  
Author(s):  
Christina Johnson ◽  
Alexis England ◽  
Mason Munro-Ehrlich ◽  
Daniel R. Colman ◽  
Jennifer L. DuBois ◽  
...  

Archaeal methanogens, methanotrophs, and alkanotrophs have a high demand for iron (Fe) and sulfur (S); however, little is known of how they acquire, traffic, deploy, and store these elements. Here, we examined the distribution of homologs of proteins mediating key steps in Fe/S metabolism in model microorganisms, including iron(II) sensing/uptake (FeoAB), sulfide extraction from cysteine (SufS), the biosynthesis of iron-sulfur [Fe-S] clusters (SufBCDE), siroheme (Pch2-dehydrogenase), protoheme (AhbABCD), and cytochrome c (CcmCF), and iron-storage/detoxification (Bfr, FtrA, IssA), among 326 publicly available, complete or metagenome-assembled genomes of archaeal methanogens/methanotrophs/alkanotrophs. Results indicate several prevalent but non-universal features including FeoB, SufBC, and the biosynthetic apparatus for the basic tetrapyrrole scaffold as well as its siroheme (and F 430 ) derivatives. However, several early diverging genomes lacked SufS and pathways to synthesize and deploy heme. Genomes encoding complete versus incomplete heme biosynthetic pathways exhibited an equivalent prevalence of [Fe-S]-cluster binding proteins, suggesting an expansion of catalytic capabilities rather than substitution of heme for [Fe-S] in the former group. Several strains with heme binding proteins lacked heme biosynthesis capabilities while other strains with siroheme biosynthesis capability lacked homologs of known siroheme binding proteins, indicating heme auxotrophy and unknown siroheme biochemistry, respectively. While ferritin proteins involved in ferric oxide storage were widespread, those involved in storing Fe as thioferrate were unevenly distributed. Collectively, the results suggest that differences in the mechanisms of Fe and S acquisition, deployment, and storage have accompanied the diversification of methanogens/methanotrophs/alkanotrophs, possibly in response to differential availability of these elements as these organisms evolved. IMPORTANCE Archaeal methanogens, methanotrophs, and alkanotrophs, argued to be among the most ancient forms of life, have a high demand for iron (Fe) and sulfur (S) for co-factor biosynthesis, among other uses. Here, using comparative bioinformatic approaches applied to 326 genomes, we show that major differences in Fe/S acquisition, trafficking, deployment, and storage exist in this group. Variation in these characters was generally congruent with the phylogenetic placement of these genomes, indicating that variation in Fe/S usage and deployment has contributed to the diversification and ecology of these organisms. However, incongruency was observed among the distribution of cofactor biosynthesis pathways and known protein destinations for those co-factors, suggesting auxotrophy or yet to be discovered pathways for cofactor biosynthesis.


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