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Instruments / Technical Area	Publication Details	Published	Actions
	XFEL crystal structures of peroxidase compound II Hanna Kwon , Jaswir Basran , Chinar Pathak , Mahdi Hussain , Samuel L. Freeman , Alistair J. Fielding , Anna J. Bailey , Natalia Stefanou , Hazel A. Sparkes , Takehiko Tosha , Keitaro Yamashita , Kunio Hirata , Hironori Murakami , Go Ueno , Hideo Ago , Kensuke Tono , Masaki Yamamoto , Hitomi Sawai , Yoshitsugu Shiro , Hiroshi Sugimoto , Emma Raven , Peter C. E. Moody Angewandte Chemie International Edition DOI: 10.1002/anie.202103010 Open Access Show Abstract ▼ Abstract: Oxygen activation in all heme enzymes requires the formation of high oxidation states of iron, usually referred to as ferryl heme. There are two known intermediates: Compound I and Compound II. The nature of the ferryl heme – and whether it is an Fe IV =O or Fe IV ‐OH species – is important for controlling reactivity across groups of heme enzymes. The most recent evidence for Compound I indicates that the ferryl heme is an unprotonated Fe IV =O species. For Compound II, the nature of the ferryl heme is not unambiguously established. Here, we report 1.06 Å and 1.50 Å crystal structures for Compound II intermediates in cytochrome c peroxidase (C c P) and ascorbate peroxidase (APX), collected using the X‐ray free electron laser at SACLA. The structures reveal differences between the two peroxidases. The iron‐oxygen bond length in C c P (1.76 Å) is notably shorter than in APX (1.87 Å). The results indicate that the ferryl species is finely tuned across Compound I and Compound II species in closely related peroxidase enzymes. We propose that this fine‐tuning is linked to the functional need for proton delivery to the heme.	Apr 2021
I03-Macromolecular Crystallography	Discovery of a heme-binding domain in a neuronal voltage-gated potassium channel Mark J Burton , Joel Cresser-Brown , Morgan Thomas , Nicola Portolano , Jaswir Basran , Samuel L. Freeman , Hanna Kwon , Andrew R. Bottrill , Manuel J Llansola-Portoles , Andrew A Pascal , Rebekah Jukes-Jones , Tatyana Chernova , Ralf Schmid , Noel W. Davies , Nina M. Storey , Pierre Dorlet , Peter C. E. Moody , John S Mitcheson , Emma L. Raven Journal Of Biological Chemistry DOI: 10.1074/jbc.RA120.014150 Diamond Proposal Number(s): [14692] Show Abstract ▼ Abstract: The ether-à-go-go (EAG) family of voltage gated K+ channels are important regulators of neuronal and cardiac action potential firing (excitability) and have major roles in human diseases such as epilepsy, schizophrenia, cancer and sudden cardiac death. A defining feature of EAG (Kv10-12) channels is a highly conserved domain on the amino-terminus, known as the eag-domain, consisting of a PAS domain capped by a short sequence containing an amphipathic helix (Cap-domain). The PAS and Cap domains are both vital for the normal function of EAG channels. Using heme-affinity pull-down assays and proteomics of lysates from primary cortical neurons, we identified that an EAG channel, hERG3 (Kv11.3), binds to heme. In whole cell electrophysiology experiments, we identified that heme inhibits hERG3 channel activity. In addition, we expressed the Cap and PAS domain of hERG3 in E.coli and, using spectroscopy and kinetics, identified the PAS domain as the location for heme binding. The results identify heme as a regulator of hERG3 channel activity. These observations are discussed in the context of the emerging role for heme as a regulator of ion channel activity in cells.	Jul 2020

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