Ferric haem forms of Mycobacterium tuberculosis catalase-peroxidase probed by EPR spectroscopy: Their stability and interplay with pH

Svistunenko, Dimitri A.; Worrall, J.A.R.; Chugh, Snehpriya B.; Haigh, S.; Ghiladi, Reza A.; Nicholls, Peter

doi:10.1016/j.biochi.2012.02.021

Cited by 13 publications

(19 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These states were differentiated from one another on the basis of the g-tensor anisotropy which was most apparent in the g ~ 6 region of the spectrum. Consistent with recent reports on ferric KatG from M. tuberculosis, 63 we observed as many as four high-spin contributors to the EPR spectra of our Group I variants. The two most easily identifiable were a species with relatively large rhombic distortion (g x ~ 6.6, g y ~ 4.95, g z ~ 1.95) and a species with relatively small rhombic distortion (g x ~ 6.0, g y ~ 5.6, and g z ~ 1.99).…”

supporting

confidence: 93%

“…In contrast, lesser degrees of rhombic distortion are taken to reflect states where water is progressively and more ideally occupying the sixth coordination site of the iron. 63 Interestingly, the utility of cyanide binding as a mimic of compound I formation arises from its similarity to formation of compound 0 by peroxide. With a pK a above 9, HCN is the dominant species in formation of the Fe III -CN complex, so H + transfer to the protein, apparently 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 22 to the distal histidine, accompanies this event.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

A Role for Catalase-Peroxidase Large Loop 2 Revealed by Deletion Mutagenesis: Control of Active Site Water and Ferric Enzyme Reactivity

Kudalkar

Njuma

et al. 2015

Biochemistry

View full text Add to dashboard Cite

Catalase-peroxidases (KatGs), the only catalase-active members of their superfamily, all possess a 35-residue interhelical loop called large loop 2 (LL2). It is essential for catalase activity, but little is known about its contribution to KatG function. LL2 shows weak sequence conservation; however, its length is nearly identical across KatGs, and its apex invariably makes contact with the KatG-unique C-terminal domain. We used site-directed and deletion mutagenesis to interrogate the role of LL2 and its interaction with the C-terminal domain in KatG structure and catalysis. Single and double substitutions of the LL2 apex had little impact on the active site heme [by magnetic circular dichroism or electron paramagnetic resonance (EPR)] and activity (catalase or peroxidase). Conversely, deletion of a single amino acid from the LL2 apex reduced catalase activity by 80%. Deletion of two or more apex amino acids or all of LL2 diminished catalase activity by 300-fold. Peroxide-dependent but not electron donor-dependent kcat/KM values for deletion variant peroxidase activity were reduced 20-200-fold, and kon for cyanide binding diminished by 3 orders of magnitude. EPR spectra for deletion variants were all consistent with an increase in the level of pentacoordinate high-spin heme at the expense of hexacoordinate high-spin states. Together, these data suggest a shift in the distribution of active site waters, altering the reactivity of the ferric state, toward, among other things, compound I formation. These results identify the importance of LL2 length conservation for maintaining an intersubunit interaction that is essential for an active site water distribution that facilitates KatG catalytic activity.

show abstract

supporting

confidence: 93%

Section: Discussionmentioning

confidence: 99%

A Role for Catalase-Peroxidase Large Loop 2 Revealed by Deletion Mutagenesis: Control of Active Site Water and Ferric Enzyme Reactivity

Kudalkar

Njuma

et al. 2015

Biochemistry

View full text Add to dashboard Cite

show abstract

“…1-methyl-1-H-pyrrole could only be detected over cultures of the reference and the S-type strain. Pyrrols represent basic components of heme complexes which can be found in protein sensor [47] and catalase/peroxidase [48] enzyme systems of the mycobacteria. The fact, that 1-methyl-1-H-pyrrole had detectable concentrations only in the laboratory adapted and the S-type field strain may hypothetically be attributed on the one hand to the (phylo)genetic differences between sheep and cattle strains and, on the other hand, to different long-term environmental conditions these bacterial strains were exposed to.…”

Section: Discussionmentioning

confidence: 99%

Volatile Emissions from Mycobacterium avium subsp. paratuberculosis Mirror Bacterial Growth and Enable Distinction of Different Strains

et al. 2013

View full text Add to dashboard Cite

Control of paratuberculosis in livestock is hampered by the low sensitivity of established direct and indirect diagnostic methods. Like other bacteria, Mycobacterium avium subsp. paratuberculosis (MAP) emits volatile organic compounds (VOCs). Differences of VOC patterns in breath and feces of infected and not infected animals were described in first pilot experiments but detailed information on potential marker substances is missing. This study was intended to look for characteristic volatile substances in the headspace of cultures of different MAP strains and to find out how the emission of VOCs was affected by density of bacterial growth. One laboratory adapted and four field strains, three of MAP C-type and one MAP S-type were cultivated on Herrold’s egg yolk medium in dilutions of 10-0, 10-2, 10-4 and 10-6. Volatile substances were pre-concentrated from the headspace over the MAP cultures by means of Solid Phase Micro Extraction (SPME), thermally desorbed from the SPME fibers and separated and identified by means of GC-MS. Out of the large number of compounds found in the headspace over MAP cultures, 34 volatile marker substances could be identified as potential biomarkers for growth and metabolic activity. All five MAP strains could clearly be distinguished from blank culture media by means of emission patterns based on these 34 substances. In addition, patterns of volatiles emitted by the reference strain were significantly different from the field strains. Headspace concentrations of 2-ethylfuran, 2-methylfuran, 3-methylfuran, 2-pentylfuran, ethyl acetate, 1-methyl-1-H-pyrrole and dimethyldisulfide varied with density of bacterial growth. Analysis of VOCs emitted from mycobacterial cultures can be used to identify bacterial growth and, in addition, to differentiate between different bacterial strains. VOC emission patterns may be used to approximate bacterial growth density. In a perspective volatile marker substances could be used to diagnose MAP infections in animals and to identify different bacterial strains and origins.

show abstract

“…[34,[37][38][39][46][47][48][49][50] To furtherc omplicate this understanding, the structure of KatG intermediates, formed during the KatG catalytic cycle, depends on pH and on the mutation studied. [36,37,51] Scheme 3s ummarizes the various proposalsf or the catalytic cycleo fK atG. [34, 37-39, 42, 46-50] Although the structureso fi ntermediates (compounds I and II)r emain uncertain, the overall mechanism is well accepted.…”

Section: Inh Activation Mechanism By Katg and Biomimetic Modelsmentioning

confidence: 99%

Update of Antitubercular Prodrugs from a Molecular Perspective: Mechanisms of Action, Bioactivation Pathways, and Associated Resistance

2017

View full text Add to dashboard Cite

The place of prodrugs in the current antitubercular therapeutic arsenal is preponderant, since two of the four first-line antitubercular agents, isoniazid (INH) and pyrazinamide (PZA), need to be activated by Mycobacterium tuberculosis before exerting their activity. In addition, six other prodrugs can be found in the second- and third-line therapeutic regimens. The emergence of mycobacterial strains resistant to one or several antitubercular agents is one of the main issues of the antitubercular therapy. In the case of prodrugs, the resistance phenomenon is often related to a mutation in the gene encoding for the activation enzymes, resulting thus in a default of these enzymes that are no more able to activate prodrugs. Consequently, identification of the prodrugs targets and a better understanding of their modes of action and also of their activation mechanisms are of crucial importance. Related to their molecular mechanism of activation, these prodrugs may thus be classified in four categories: activation via oxidation (catalase-peroxidase (KatG) or flavin monooxygenase (EthA) enzymes), condensation (FolP1 and FolC), hydrolysis (by the amidase PncA) and reduction (by the nitroreductase DnD) mechanisms. For each prodrug, these mechanisms are described in details, as well as the mechanism of action of its active metabolite. Finally, the reported resistance related to these mechanisms of activation/action are also addressed in a molecular perspective.

show abstract

Ferric haem forms of Mycobacterium tuberculosis catalase-peroxidase probed by EPR spectroscopy: Their stability and interplay with pH

Cited by 13 publications

References 27 publications

A Role for Catalase-Peroxidase Large Loop 2 Revealed by Deletion Mutagenesis: Control of Active Site Water and Ferric Enzyme Reactivity

A Role for Catalase-Peroxidase Large Loop 2 Revealed by Deletion Mutagenesis: Control of Active Site Water and Ferric Enzyme Reactivity

Volatile Emissions from Mycobacterium avium subsp. paratuberculosis Mirror Bacterial Growth and Enable Distinction of Different Strains

Update of Antitubercular Prodrugs from a Molecular Perspective: Mechanisms of Action, Bioactivation Pathways, and Associated Resistance

Contact Info

Product

Resources

About