Muro-Pastor AM, Valladares A, Flores E, Herrero A (2002) Mutual dependence of the expression of the cell differentiation regulatory protein HetR and the global nitrogen regulator NtcA during heterocyst development. Mol microbiol 44: 1377–1385. pmid:12068814 Li JH (2003) An increase in the level of 2-oxoglutarate promotes heterocyst development in the cyanobacterium Anabaena sp. strain PCC 7120. Microbiology 149: 3257–3263. pmid:14600238

Table 1. Parameters for Eq. (11) that reproduce heterocyst formation under noisy conditions and pattern formation when PatS and cN diffuse along a filament of cyanobacteria. Yoon HS, Golden JW: PatS and products of nitrogen fixation control heterocyst pattern. J Bacteriol. 2001, 183 (8): 2605-2613. 10.1128/JB.183.8.2605-2613.2001.To confirm this interaction, we developed a BioLayer interferometry (BLi) assay. For this purpose, HetR and HetL proteins were produced and purified using affinity chromatography ( Figure 1—figure supplement 1). HetR was biotinylated and immobilized on streptavidin biosensors as the ligand, while HetL was used as the analyte. Upon addition of HetL, a concentration-dependent association was recorded and decreased during the dissociation step corresponding to the washing of the sensor, indicating a direct interaction between HetL and HetR ( Figure 1C). The estimated dissociation constant (K D) of the HetR-HetL interaction was 6 µM. The interaction between HetR and HetL observed in the BACTH assay was thus confirmed by BLi. It was important for us to choose a title which highlights the novelty that our study brings in relation to the state of art in the field. Nonetheless, we understand the importance of broad-significance titles and therefore decided to adopt the proposed one. SARS-CoV-2 spike protein plays a key role in mediating viral entry and inducing host immune responses. It can adopt either an open or closed conformation based on the position of its receptor-binding domain (RBD). It is yet unclear what cause these conformational changes or how they influence the spike's functions. Here we show that Lys417 in the RBD plays dual roles in the spike's structure: it stabilizes the closed conformation of the trimeric spike by mediating inter-spike-subunit interactions; it also directly interacts with ACE2 receptor. Hence, a K417V mutation has opposing effects on the spike's function: it opens up the spike for better ACE2 binding while weakening the RBD's direct binding to ACE2. The net outcomes of this mutation are to allow the spike to bind ACE2 with higher probability, mediate viral entry more efficiently, but become more exposed to neutralizing antibodies. Given that residue 417 has been a viral mutational hotspot, SARS-CoV-2 may have been evolving to strike a balance between infection potency and immune evasion, contributing to its pandemic spread.

Mitchison GJ, Smith RJ, Road H (1973) Pattern formation in the blue-green alga, anabaena. I. Basic Mechanisms. J Cell Sci 12: 707–723. pmid:4198321 The HETR was launched by Deputy Prime Minister Datuk Seri Fadillah Yusof during the opening ceremony of the 14th International Greentech and Eco Products Exhibition and Conference Malaysia (IGEM 2023) today. X-ray diffraction data were collected at 100 K in a liquid nitrogen stream, using beamline BL17U with a Q315r CCD (ADSC, MARresearch, Germany) at the Shanghai Synchrotron Radiation Facility (SSRF). All diffraction data were integrated and scaled with the program HKL2000 35. Structure determination and refinement

Author Contributions

By reducing the flow of cN from the exterior of the cell ( l n = 0) we find that a stable fixed point appears in the upper branch, a heterocyst state, while the vegetative state gets closer to the bifurcation region, thus becoming more susceptible to perturbations that can make the system reach the upper branch. In the absence of cN, the cyanobacterium would evolve from state A to state B in the lower branch until a perturbation pushes it to the upper branch, eventually becoming an heterocyst due to the field acting on that branch ( Fig. 5B and C). The hetR gene from Anabaena sp. PCC 7120 was cloned into a modified pET28 vector with a six-histidine tag at the N-terminus. The DNA sequence encoding HetR Hood (Asp219-Asp299) was also cloned into this pET28a-derived vector. The two recombinant plasmids were validated by DNA sequencing (Sangon Biotech, Shanghai). HetR and HetR Hood proteins were overexpressed in Escherichia coli strain Rosetta (DE3) (Novagen, Madison). Cells were grown in 2 × YT medium (5 g NaCl, 16 g Bacto-Tryptone and 10 g yeast extract per liter) at 37 °C containing kanamycin and chloramphenicol at 30 and 34 μg/ml, respectively. At an OD 600 nm of 0.8, protein expression was induced with 0.2 mM isopropyl β-D-1-thiogalactopyranoside at 16 °C for 20 hr. Cells were harvested by centrifugation (6,000 × g, 4 °C, 10 min) and resuspended in 40 ml lysis buffer (1 M NaCl, 10 mM Tris-Cl, pH 7.8). After 5 min of sonication and centrifugation at 12,000 × g for 30 min, the supernatant containing the soluble target protein was pooled and loaded onto a Ni-NTA column (Qiagen, Mississauga, ON) equilibrated with the binding buffer (1 M NaCl, 10 mM Tris-Cl, pH 7.8). The target protein was eluted with 300 mM imidazole and further applied to a Superdex 75 column (GE Healthcare, UK) equilibrated with the binding buffer. The purity of protein was assessed by gel electrophoresis and the protein sample was stored at −80 °C. Schneider CA, Rasband WS, Eliceiri KW: NIH Image to ImageJ: 25 years of image analysis. Nat Methods. 2012, 9 (7): 671-675. 10.1038/nmeth.2089. Here, Xu et al. show that HetL cannot diffuse from one cell to the other, and that it binds to HetR at the same place than PatS does. When both PatS and HetL are present, they compete to attach to HetR, which stops PatS from turning off HetR and deactivating the nitrogen-fixing program. Alfonso M, Kirilovsky D (2001) Redox Control of ntcA Gene Expression in Synechocystis sp. PCC 6803. Nitrogen Availability and NtcA Protein 1. Plant Physiol 125: 969–981. pmid:11161053

The Creative Commons Public Domain Dedication waiver ( https://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Golden JW, Whorff LL, Wiest DR: Independent regulation of nifHDK operon transcription and DNA rearrangement during heterocyst differentiation in the cyanobacterium Anabaena sp. strain PCC 7120. J Bacteriol. 1991, 173 (22): 7098-7105.

Abstract

With the implementation of initiatives under the recently unveiled National Energy Transition Roadmap (NETR) and (now) the HETR, Malaysia is set to be at the forefront of becoming a regional leader in the energy transition and renewable energy industry,” he said at the launch of IGEM 2023. Flores E, Herrero A (2010) Compartmentalized function through cell differentiation in filamentous cyanobacteria. Nat Rev Microbiol 8: 39–50. DOI: https://doi.org/10.1038/nrmicro2242. Feldmann, E. A. et al. Differential binding between PatS C-terminal peptide fragments and HetR from Anabaena sp. PCC 7120. Biochemistry 51, 2436–42 (2012).