Editing Hemerythrin (section)

==Hemerythrin/HHE cation-binding domain==
The hemerythrin/HHE cation-binding [[protein domain|domain]] occurs as a duplicated domain in hemerythrins, myohemerythrins and related proteins. This domain binds [[iron]] in hemerythrin, but can bind other metals in related proteins, such as [[cadmium]] in the ''[[Nereis diversicolor]]'' hemerythrin. It is also found in the NorA protein from ''[[Cupriavidus necator]]'', this protein is a regulator of response to [[nitric oxide]], which suggests a different set-up for its metal [[ligands]]. A protein from ''[[Cryptococcus neoformans]]'' (Filobasidiella neoformans) that contains haemerythrin/HHE cation-binding domains is also involved in nitric oxide response.<ref name="pmid17661046">{{cite journal |vauthors=Chow ED, Liu OW, O'Brien S, Madhani HD | title = Exploration of whole-genome responses of the human AIDS-associated yeast pathogen Cryptococcus neoformans var grubii: nitric oxide stress and body temperature | journal = Curr. Genet. | volume = 52 | issue = 3–4 | pages = 137–48 |date=September 2007 | pmid = 17661046 | doi = 10.1007/s00294-007-0147-9 | s2cid = 10212964 }}</ref> A ''[[Staphylococcus aureus]]'' protein containing this domain, iron-sulfur cluster repair protein ScdA, has been noted to be important when the [[organism]] switches to living in environments with low oxygen concentrations; perhaps this protein acts as an oxygen store or scavenger.<ref name="pmid18203837">{{cite journal |vauthors=Overton TW, Justino MC, Li Y, Baptista JM, Melo AM, Cole JA, etal | title=Widespread Distribution in Pathogenic Bacteria of Di-Iron Proteins That Repair Oxidative and Nitrosative Damage to Iron-Sulfur Centers | journal=J Bacteriol | year= 2008 | volume= 190 | issue= 6 | pages= 2004–13 | pmid=18203837 | doi=10.1128/JB.01733-07 | pmc=2258886   }}</ref>

Hemerythrin/HHE (H-HxxxE-HxxxH-HxxxxD) proteins found in bacteria are implicated in signal transduction and [[chemotaxis]]. More distantly related ones include H-HxxxE-H-HxxxE proteins (including the [[E3 ligase]]) and animal [[F-box protein]]s (H-HExxE-H-HxxxE).<ref>{{cite journal |last1=Alvarez-Carreño |first1=Claudia |last2=Alva |first2=Vikram |last3=Becerra |first3=Arturo |last4=Lazcano |first4=Antonio |title=Structure, function and evolution of the hemerythrin-like domain superfamily: Hemerythrin-like Domain Superfamily |journal=Protein Science |date=April 2018 |volume=27 |issue=4 |pages=848–860 |doi=10.1002/pro.3374|pmid=29330894 |pmc=5866928 |doi-access=free }}</ref>