FEBS Letters

doi: 10.1002/1873-3468.14382pmid: N/A

Walton, Paul H.; Davies, Gideon J.; Diaz, Daniel E.; Franco‐Cairo, João P.

doi: 10.1002/1873-3468.14579pmid: 36660911

The copper histidine brace is a structural unit in metalloproteins (Proc Natl Acad Sci USA 2011, 108, 15079). It consists of a copper ion chelated by the NH2 and π‐N atom of an N‐terminal histidine, and the τ‐N atom of a further histidine, in an overall T‐shaped coordination geometry (Nat Catal 2018, 1, 571). Like haem‐containing proteins, histidine‐brace‐containing proteins have peroxygenase and/or oxygenase activity, where the substrates are notable for resistance to oxidation, for example, lytic polysaccharide monooxygenases (LPMOs). Moreover, the histidine brace is an invariant unit around which different protein structures exert different activities. Given the similarities in the diversity of function of proteins that contain either the copper histidine brace or haem, the question arises as to whether the functions of histidine brace‐containing proteins duplicate those containing haem groups.

Šťastný, Dominik; Petrisková, Lívia; Tahotná, Dana; Bauer, Jacob; Pokorná, Lucia; Holič, Roman; Valachovič, Martin; Pevala, Vladimír; Cockcroft, Shamshad; Griač, Peter

doi: 10.1002/1873-3468.14558pmid:

Goojani, Hojjat Ghasemi; Besharati, Samira; Chauhan, Priyanka; Asseri, Amer H.; Lill, Holger; Bald, Dirk

doi: 10.1002/1873-3468.14550pmid: 36460943

Cytochrome bd‐I from Escherichia coli is a terminal oxidase in the respiratory chain that plays an important role under stress conditions. Cytochrome bd‐I was thought to consist of the major subunits CydA and CydB plus the small CydX subunit. Recent high‐resolution structures of cytochrome bd‐I demonstrated the presence of an additional subunit, CydH/CydY (called CydH here), the function of which is unclear. In this report, we show that in the absence of CydH, cytochrome bd‐I is catalytically active, can sustain bacterial growth and displays haem spectra and susceptibility for haem‐binding inhibitors comparable to the wild‐type enzyme. Removal of CydH did not elicit catalase activity of cytochrome bd‐I in our experimental system. Taken together, in the absence of the CydH subunit cytochrome bd‐I retained key enzymatic properties.

Wooldridge, Rowan; Stone, Spenser; Pedraza, Andrew; Ray, W. Keith; Helm, Richard F.; Allen, Kylie D.

doi: 10.1002/1873-3468.14573pmid: 36647787

CADD (chlamydia protein associating with death domains) is a p‐aminobenzoate (pAB) synthase involved in a noncanonical route for tetrahydrofolate biosynthesis in Chlamydia trachomatis. Although previously implicated to employ a diiron cofactor, here, we show that pAB synthesis by CADD requires manganese and the physiological cofactor is most likely a heterodinuclear Mn/Fe cluster. Isotope‐labeling experiments revealed that the two oxygen atoms in the carboxylic acid portion of pAB are derived from molecular oxygen. Further, mass spectrometry‐based proteomic analyses of CADD‐derived peptides demonstrated a glycine substitution at Tyr27, providing strong evidence that this residue is sacrificed for pAB synthesis. Additionally, Lys152 was deaminated and oxidized to aminoadipic acid, supporting its proposed role as a sacrificial amino group donor.

Yamaji, Kotaro; Taniguchi, Rumine; Urano, Hiroyuki; Ogasawara, Hiroshi

doi: 10.1002/1873-3468.14574pmid: 36647922

Sensor histidine kinase HprS, an oxidative stress sensor of Escherichia coli, senses reactive oxygen species (ROS) and reactive chlorine species (RCS), and is involved in the induction of oxidatively damaged protein repair periplasmic enzymes. We reinvestigated the roles of six methionine and four cysteine residues of HprS in the response to HClO, an RCS. The results of site‐directed mutagenesis revealed that methionine residues in periplasmic and cytoplasmic regions (Met225) are involved in HprS activation. Interestingly, the Cys165Ser substitution reduced HprS activity, which was recovered by an additional Glu22Cys substitution. Our results demonstrate that the position of the inner membrane cysteine residues influences the extent of HprS activation in HClO sensing.

Torresi, Florencia; Rodriguez, Fernanda M.; Gomez‐Casati, Diego F.; Martín, Mariana

doi: 10.1002/1873-3468.14590pmid: 36708098

Phosphoenolpyruvate carboxykinase (PEPCK) catalyses the reversible reaction of decarboxylation and phosphorylation of oxaloacetate (OAA) to generate phosphoenolpyruvate (PEP) and CO2 playing mainly a gluconeogenic role in green algae. We found two PEPCK isoforms in Chlamydomonas reinhardtii and we cloned, purified and characterised both enzymes. ChlrePEPCK1 is more active as decarboxylase than ChlrePEPCK2. ChlrePEPCK1 is hexameric and its activity is affected by citrate, phenylalanine and malate, while ChlrePEPCK2 is monomeric and it is regulated by citrate, phenylalanine and glutamine. We postulate that the two PEPCK isoforms found originate from alternative splicing of the gene or regulated proteolysis of the enzyme. The presence of these two isoforms would be part of a mechanism to finely regulate the biological activity of PEPCKs.