An unconventional hexacoordinated flavohemoglobin from Mycobacterium tuberculosis

Sanjay Gupta, Sudesh Pawaria, Changyuan Lu, Mangesh Dattu Hade, Chaahat Singh, Syun-Ru Yeh, Kanak L. Dikshit

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Being an obligate aerobe, Mycobacterium tuberculosis faces a number of energetic challenges when it encounters hypoxia and environmental stress during intracellular infection. Consequently, it has evolved innovative strategies to cope with these unfavorable conditions. Here, we report a novel flavohemoglobin (MtbFHb) from M. tuberculosis that exhibits unique features within its heme and reductase domains distinct from conventional FHbs, including the absence of the characteristic hydrogen bonding interactions within the proximal heme pocket and mutations in the FAD and NADH binding regions of the reductase domain. In contrast to conventional FHbs, it has a hexacoordinate low-spin heme with a proximal histidine ligand lacking imidazolate character and a distal heme pocket with a relatively low electrostatic potential. Additionally, MtbFHb carries a new FAD binding site in its reductase domain similar to that of D-lactate dehydrogenase (D-LDH). When overexpressed in Escherichia coli or Mycobacterium smegmatis, MtbFHb remained associated with the cell membrane and exhibited D-lactate:phenazine methosulfate reductase activity and oxidized D-lactate into pyruvate by converting the heme iron from Fe3+ to Fe2+ in a FAD-dependent manner, indicating electron transfer from D-lactate to the heme via FAD cofactor. Under oxidative stress, MtbFHb-expressing cells exhibited growth advantage with reduced levels of lipid peroxidation. Given the fact that D-lactate is a byproduct of lipid peroxidation and that M. tuberculosis lacks the gene encoding D-LDH, we propose that the novel D-lactate metabolizing activity of MtbFHb uniquely equips M. tuberculosis to balance the stress level by protecting the cell membrane from oxidative damage via cycling between the Fe3+/Fe2+ redox states.

Original languageEnglish (US)
Pages (from-to)16435-16446
Number of pages12
JournalJournal of Biological Chemistry
Volume287
Issue number20
DOIs
StatePublished - May 11 2012

Fingerprint

Heme
Mycobacterium tuberculosis
Flavin-Adenine Dinucleotide
Lactic Acid
Oxidoreductases
Cell membranes
Lipid Peroxidation
Methylphenazonium Methosulfate
Cell Membrane
Mycobacterium smegmatis
Lipids
Gene encoding
Oxidative stress
Cell growth
Hydrogen Bonding
Static Electricity
Pyruvic Acid
Histidine
NAD
Escherichia coli

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Cite this

An unconventional hexacoordinated flavohemoglobin from Mycobacterium tuberculosis. / Gupta, Sanjay; Pawaria, Sudesh; Lu, Changyuan; Hade, Mangesh Dattu; Singh, Chaahat; Yeh, Syun-Ru; Dikshit, Kanak L.

In: Journal of Biological Chemistry, Vol. 287, No. 20, 11.05.2012, p. 16435-16446.

Research output: Contribution to journalArticle

Gupta, S, Pawaria, S, Lu, C, Hade, MD, Singh, C, Yeh, S-R & Dikshit, KL 2012, 'An unconventional hexacoordinated flavohemoglobin from Mycobacterium tuberculosis', Journal of Biological Chemistry, vol. 287, no. 20, pp. 16435-16446. https://doi.org/10.1074/jbc.M111.329920
Gupta, Sanjay ; Pawaria, Sudesh ; Lu, Changyuan ; Hade, Mangesh Dattu ; Singh, Chaahat ; Yeh, Syun-Ru ; Dikshit, Kanak L. / An unconventional hexacoordinated flavohemoglobin from Mycobacterium tuberculosis. In: Journal of Biological Chemistry. 2012 ; Vol. 287, No. 20. pp. 16435-16446.
@article{188a0cd9794b481ba7371115adc01d87,
title = "An unconventional hexacoordinated flavohemoglobin from Mycobacterium tuberculosis",
abstract = "Being an obligate aerobe, Mycobacterium tuberculosis faces a number of energetic challenges when it encounters hypoxia and environmental stress during intracellular infection. Consequently, it has evolved innovative strategies to cope with these unfavorable conditions. Here, we report a novel flavohemoglobin (MtbFHb) from M. tuberculosis that exhibits unique features within its heme and reductase domains distinct from conventional FHbs, including the absence of the characteristic hydrogen bonding interactions within the proximal heme pocket and mutations in the FAD and NADH binding regions of the reductase domain. In contrast to conventional FHbs, it has a hexacoordinate low-spin heme with a proximal histidine ligand lacking imidazolate character and a distal heme pocket with a relatively low electrostatic potential. Additionally, MtbFHb carries a new FAD binding site in its reductase domain similar to that of D-lactate dehydrogenase (D-LDH). When overexpressed in Escherichia coli or Mycobacterium smegmatis, MtbFHb remained associated with the cell membrane and exhibited D-lactate:phenazine methosulfate reductase activity and oxidized D-lactate into pyruvate by converting the heme iron from Fe3+ to Fe2+ in a FAD-dependent manner, indicating electron transfer from D-lactate to the heme via FAD cofactor. Under oxidative stress, MtbFHb-expressing cells exhibited growth advantage with reduced levels of lipid peroxidation. Given the fact that D-lactate is a byproduct of lipid peroxidation and that M. tuberculosis lacks the gene encoding D-LDH, we propose that the novel D-lactate metabolizing activity of MtbFHb uniquely equips M. tuberculosis to balance the stress level by protecting the cell membrane from oxidative damage via cycling between the Fe3+/Fe2+ redox states.",
author = "Sanjay Gupta and Sudesh Pawaria and Changyuan Lu and Hade, {Mangesh Dattu} and Chaahat Singh and Syun-Ru Yeh and Dikshit, {Kanak L.}",
year = "2012",
month = "5",
day = "11",
doi = "10.1074/jbc.M111.329920",
language = "English (US)",
volume = "287",
pages = "16435--16446",
journal = "Journal of Biological Chemistry",
issn = "0021-9258",
publisher = "American Society for Biochemistry and Molecular Biology Inc.",
number = "20",

}

TY - JOUR

T1 - An unconventional hexacoordinated flavohemoglobin from Mycobacterium tuberculosis

AU - Gupta, Sanjay

AU - Pawaria, Sudesh

AU - Lu, Changyuan

AU - Hade, Mangesh Dattu

AU - Singh, Chaahat

AU - Yeh, Syun-Ru

AU - Dikshit, Kanak L.

PY - 2012/5/11

Y1 - 2012/5/11

N2 - Being an obligate aerobe, Mycobacterium tuberculosis faces a number of energetic challenges when it encounters hypoxia and environmental stress during intracellular infection. Consequently, it has evolved innovative strategies to cope with these unfavorable conditions. Here, we report a novel flavohemoglobin (MtbFHb) from M. tuberculosis that exhibits unique features within its heme and reductase domains distinct from conventional FHbs, including the absence of the characteristic hydrogen bonding interactions within the proximal heme pocket and mutations in the FAD and NADH binding regions of the reductase domain. In contrast to conventional FHbs, it has a hexacoordinate low-spin heme with a proximal histidine ligand lacking imidazolate character and a distal heme pocket with a relatively low electrostatic potential. Additionally, MtbFHb carries a new FAD binding site in its reductase domain similar to that of D-lactate dehydrogenase (D-LDH). When overexpressed in Escherichia coli or Mycobacterium smegmatis, MtbFHb remained associated with the cell membrane and exhibited D-lactate:phenazine methosulfate reductase activity and oxidized D-lactate into pyruvate by converting the heme iron from Fe3+ to Fe2+ in a FAD-dependent manner, indicating electron transfer from D-lactate to the heme via FAD cofactor. Under oxidative stress, MtbFHb-expressing cells exhibited growth advantage with reduced levels of lipid peroxidation. Given the fact that D-lactate is a byproduct of lipid peroxidation and that M. tuberculosis lacks the gene encoding D-LDH, we propose that the novel D-lactate metabolizing activity of MtbFHb uniquely equips M. tuberculosis to balance the stress level by protecting the cell membrane from oxidative damage via cycling between the Fe3+/Fe2+ redox states.

AB - Being an obligate aerobe, Mycobacterium tuberculosis faces a number of energetic challenges when it encounters hypoxia and environmental stress during intracellular infection. Consequently, it has evolved innovative strategies to cope with these unfavorable conditions. Here, we report a novel flavohemoglobin (MtbFHb) from M. tuberculosis that exhibits unique features within its heme and reductase domains distinct from conventional FHbs, including the absence of the characteristic hydrogen bonding interactions within the proximal heme pocket and mutations in the FAD and NADH binding regions of the reductase domain. In contrast to conventional FHbs, it has a hexacoordinate low-spin heme with a proximal histidine ligand lacking imidazolate character and a distal heme pocket with a relatively low electrostatic potential. Additionally, MtbFHb carries a new FAD binding site in its reductase domain similar to that of D-lactate dehydrogenase (D-LDH). When overexpressed in Escherichia coli or Mycobacterium smegmatis, MtbFHb remained associated with the cell membrane and exhibited D-lactate:phenazine methosulfate reductase activity and oxidized D-lactate into pyruvate by converting the heme iron from Fe3+ to Fe2+ in a FAD-dependent manner, indicating electron transfer from D-lactate to the heme via FAD cofactor. Under oxidative stress, MtbFHb-expressing cells exhibited growth advantage with reduced levels of lipid peroxidation. Given the fact that D-lactate is a byproduct of lipid peroxidation and that M. tuberculosis lacks the gene encoding D-LDH, we propose that the novel D-lactate metabolizing activity of MtbFHb uniquely equips M. tuberculosis to balance the stress level by protecting the cell membrane from oxidative damage via cycling between the Fe3+/Fe2+ redox states.

UR - http://www.scopus.com/inward/record.url?scp=84860852646&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84860852646&partnerID=8YFLogxK

U2 - 10.1074/jbc.M111.329920

DO - 10.1074/jbc.M111.329920

M3 - Article

VL - 287

SP - 16435

EP - 16446

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 20

ER -