Search

To survive in the iron-devoid environment of their host, pathogenic bacteria have devised multifarious cunning tactics such as evolving intricate heme transport systems to pirate extracellular heme. Yet, the potential of heme transport systems as antimicrobial targets has not been explored. Herein we developed a strategy to deliver antimicrobials by exploiting the extracellular heme acquisition system protein A (HasA) of Pseudomonas aeruginosa . We demonstrated that, analogous to heme uptake, HasA can specifically traffic an antimicrobial, gallium phthalocyanine (GaPc), into the intracellular space of P. aeruginosa via , permitting its sterilization (>99.99%) by irradiation with near-infrared (NIR) light, irrespective of antibiotic resistance. Our findings substantiate that bacterial heme uptake P. aeruginosa , permitting its sterilization (>99.99%) by irradiation with near-infrared (NIR) light, irrespective of antibiotic resistance. Our findings substantiate that bacterial heme uptake via protein-protein recognition is an attractive target for antimicrobials, enabling specific and effective sterilization.

The heme acquisition system A protein secreted by Pseudomonas aeruginosa (HasA(p)) can capture several synthetic metal complexes other than heme. The crystal structures of HasA(p) harboring synthetic metal complexes revealed only small perturbation of the overall HasA(p) structure. An inhibitory effect upon heme acquisition by HasA(p) bearing synthetic metal complexes was examined by monitoring the growth of Pseudomonas aeruginosa PAO1. HasA(p) bound to iron-phthalocyanine inhibits heme acquisition in the presence of heme-bound HasA(p) as an iron source., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Using artificial hemes for the reconstruction of natural heme proteins represents a fascinating approach to enhance the bioactivity of the latter. We report the synthesis of various metal 5‐oxaporphyrinium cations as cofactors, and a cobalt 5‐oxaporphyrinium cation was successfully incorporated into the heme‐acquisition protein (HasA) secreted by Pseudomonas aeruginosa. We hypothesize that the oxaporphyrinium cation strongly binds to the HasA‐specific outer membrane receptor (HasR) due to its cationic charge, which prevents the subsequent acquisition of heme. In fact, the reconstructed HasA inhibited the growth of Pseudomonas aeruginosa and even of multidrug‐resistant P. aeruginosa. [ABSTRACT FROM AUTHOR]

Despite CYP102A1 (P450BM3) representing one of the most extensively researched metalloenzymes, crystallisation of its haem domain upon modification can be a challenge. Crystal structures are indispensable for the efficient structure‐based design of P450BM3 as a biocatalyst. The abietane diterpenoid derivative N‐abietoyl‐l‐tryptophan (AbiATrp) is an outstanding crystallisation accelerator for the wild‐type P450BM3 haem domain, with visible crystals forming within 2 hours and diffracting to a near‐atomic resolution of 1.22 Å. Using these crystals as seeds in a cross‐microseeding approach, an assortment of P450BM3 haem domain crystal structures, containing previously uncrystallisable decoy molecules and diverse artificial metalloporphyrins binding various ligand molecules, as well as heavily tagged haem‐domain variants, could be determined. Some of the structures reported herein could be used as models of different stages of the P450BM3 catalytic cycle. [ABSTRACT FROM AUTHOR]

The heme of hydrogen peroxide-dependent cytochrome P450BSβ (P450BSβ) was removed by apomyoglobin under mild conditions to give apo-P450BSβ without the need for acidic conditions and organic solvents. The circular dichroism spectrum of the apo-P450BSβ was essentially identical to that of holo-P450BSβ, showing a small structural change resulting from the removal of heme using apomyoglobin. The apo-P450BSβ was reconstituted with hemin or manganese protoporphyrin IX (MnPPIX), and the resulting reconstituted P450BSβ catalyzed the one-electron oxidation of guaiacol using hydrogen peroxide as an oxidant. A higher catalytic activity was observed for P450BSβ reconstituted with MnPPIX when meta-chloroperoxybenzoic acid (mCPBA) was used as the oxidant. [ABSTRACT FROM AUTHOR]

[Display omitted] • The critical function of haem-acquisition system of gram-negative bacterial pathogens. • Artificial haem-acquisition protein HasAs harbouring synthetic metal complexes and their crystal structure analysis. • Antimicrobial applications of HasA capturing synthetic complexes. • Chemical applications of artificial-HasAs including catalytic utilities. Certain bacterial pathogens secrete haemophores, i.e. extracellular haem-uptake proteins, which acquire haem as a vital source of iron in the iron-devoid environment of their hosts. The haem-binding site of haemophores is highly exposed to the protein surface, enabling them to pirate haem from other haem-containing proteins (haemoproteins). This review will discuss the hidden ability of a representative haemophore, namely the haem-acquisition system protein A (HasA) secreted by Pseudomonas aeruginosa , which can accommodate a diverse assortment of synthetic metal complexes possessing extreme insolubility and/or high steric bulk in its haem-binding site. The replacement of haem with similar synthetic analogues is an already well established and powerful means to change the function of select haemoproteins; however, usable complexes are severely limited by the high selectivity of haemoproteins for haem. This review will introduce how combining the haem-replacement approach with HasA can open the door for the biological application of diverse synthetic metal complexes that were previously incompatible with biological systems. [ABSTRACT FROM AUTHOR]

The heme acquisition system A protein secreted by Pseudomonas aeruginosa (HasAp) can capture several synthetic metal complexes other than heme. The crystal structures of HasAp harboring synthetic metal complexes revealed only small perturbation of the overall HasAp structure. An inhibitory effect upon heme acquisition by HasAp bearing synthetic metal complexes was examined by monitoring the growth of Pseudomonas aeruginosa PAO1. HasAp bound to iron-phthalocyanine inhibits heme acquisition in the presence of heme-bound HasAp as an iron source. [ABSTRACT FROM AUTHOR]

Cytochrome P450SPα (CYP152B1) isolated from Sphingomonas paucimobilis is the first P450 to be classified as a H2O2-dependent P450. P450SPα hydroxylates fatty acids with high α-regioselectivity. Herein we report the crystal structure of P450SPα with palmitic acid as a substrate at a resolution of 1.65 Å. The structure revealed that the Ca of the bound palmitic acid in one of the alternative conformations is 4.5 Å from the heme iron. This conformation explains the highly selective α-hydroxylation of fatty acid observed in P450SPα. Mutations at the active site and the F-G loop of P450SPα did not impair its regioselectivity. The crystal structures of mutants (L78F and F288G) revealed that the location of the bound palmitic acid was essentially the same as that in the WT, although amino acids at the active site were replaced with the corresponding amino acids of cytochrome P450BSβ (CYP152A1), which shows β-regioselectivity. This implies that the high regioselectivity of P450SPα is caused by the orientation of the hydrophobic channel, which is more perpendicular to the heme plane than that of P450BSβ. [ABSTRACT FROM AUTHOR]

Inside Back Cover: A Heme-Acquisition Protein Reconstructed with a Cobalt 5-Oxaporphyrinium Cation and Its Growth-Inhibition Activity Toward Multidrug-Resistant Pseudomonas aeruginosa (Angew. Cobalt, Heme, Multidrug-Resistant Pseudomonas Aeruginosa, Porphyrinoid, Reconstructed Protein Keywords: Cobalt; Heme; Multidrug-Resistant Pseudomonas Aeruginosa; Porphyrinoid; Reconstructed Protein EN Cobalt Heme Multidrug-Resistant Pseudomonas Aeruginosa Porphyrinoid Reconstructed Protein 1 1 1 02/03/22 20220207 NES 220207 B The purple cloud b (HasA; a heme acquisition protein) delivers cobalt oxaporphyrinium (orange porphyrin and red oxygen) to I Pseudomonas aeruginosa i (green). [Extracted from the article]

Keywords: Cobalt; Heme; Multidrug-Resistant Pseudomonas Aeruginosa; Porphyrinoid; Reconstructed Protein EN Cobalt Heme Multidrug-Resistant Pseudomonas Aeruginosa Porphyrinoid Reconstructed Protein 1 1 1 02/03/22 20220207 NES 220207 B Die violette Wolke b (HasA; ein Häm-Akquisitionsprotein) liefert Cobalt-Oxaporphyrinium (oranges Porphyrin und roter Sauerstoff) zu I Pseudomonas aeruginosa i (grün). Innenrücktitelbild: A Heme-Acquisition Protein Reconstructed with a Cobalt 5-Oxaporphyrinium Cation and Its Growth-Inhibition Activity Toward Multidrug-Resistant Pseudomonas aeruginosa (Angew. Cobalt, Heme, Multidrug-Resistant Pseudomonas Aeruginosa, Porphyrinoid, Reconstructed Protein. [Extracted from the article]

Cytochrome P450BM3 has long been regarded as a promising candidate for use as a biocatalyst, owing to its excellent efficiency for the hydroxylation of unactivated C–H bonds. However, because of its high substrate specificity, its possible applications have been severely limited. Consequently, various approaches have been proposed to overcome the enzyme's natural limitations, thereby expanding its substrate scope to encompass non-native substrates, evoking chemoselectivity, regioselectivity and stereoselectivity and enabling previously inaccessible chemical conversions. Herein, these approaches will be classified into three categories: (1) mutagenesis including directed evolution, (2) haem substitution with artificial cofactors and (3) use of substrate mimics, 'decoy molecules'. Herein, we highlight the representative work that has been conducted in above three categories for discussion of the future outlook of P450BM3 in green chemistry. [ABSTRACT FROM AUTHOR]

Cytochrome P450 enzymes (CYPs) have attracted much promise as biocatalysts in a push for cleaner and more environmentally friendly catalytic systems. However, changing the substrate specificity of CYPs, such as CYP102A1, can be a challenging task, requiring laborious mutagenesis. An alternative approach is the use of decoy molecules that "trick" the enzyme into becoming active by impersonating the native substrate. Whilst the decoy molecule system has been extensively developed for CYP102A1, its general applicability for other CYP102-family enzymes has yet to be shown. Herein, we demonstrate that decoy molecules can "trick" CYP102A5 and A7 into becoming active and hydroxylating non-native substrates. Furthermore, significant differences in decoy molecule selectivity as well as decoy molecule binding were observed. The X-ray crystal structure of the CYP102A5 haem domain was solved at 2.8 Å, delivering insight into a potential substate-binding site that differs significantly from CYP102A1. Decoy molecules were shown to be compatible for use with both CYP102A5 and CYP102A7. Both CYP102A5 and CYP102A7 displayed a unique and unexpected decoy molecule preference. The crystal structure of CYP102A5 was solved at a resolution of 2.8 Å. [Display omitted] • Decoy molecules were shown to be compatible for use with both CYP102A5 and A7. • Both CYP102A5 and A7 displayed a unique and unexpected decoy molecule preference. • Decoy molecules were found to bind in a two-step fashion to CYP102A5 and A7 that was not observed for A1. • We report the first structure of CYP102A5 at a resolution of 2.8 Å. • The structure of CYP102A5 reveals a potential binding site that differs significantly from the CYP102A1 reference system. [ABSTRACT FROM AUTHOR]