''o''-Succinylbenzoate—CoA ligase (), encoded from the menE gene in ''Escherichia coli'', catalyzes the fifth reaction in the synthesis of menaquinone (vitamin K2). This pathway is called 1, 4-dihydroxy-2-naphthoate biosynthesis I. Vitamin K is a

quinone The quinones are a class of organic compounds that are formally "derived from aromatic compounds

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by conversion of an even number of –CH= groups into –C(=O)– groups with any necessary rearrangement of double ...

that serves as an electron transporter during anaerobic respiration. This process of anaerobic respiration allows the bacteria to generate the energy required to survive.

Background

The systematic name for the MenE enzyme is ''2-succinylbenzoate: CoA ligase (AMP-forming)''. Other names for this enzyme include: o-succinylbenzoate-CoA synthase; o-succinylbenzoyl-coenzyme A synthetase; OSB-CoA synthetase; OSB: CoA ligase; synthetase, and o-succinylbenzoyle coenzyme A. The EC number is 6.2.1.26. MenE belongs to the ligase enzyme family, or class 6. In the presence of 0.5mM of Ca(2+), K(+), Na(+), and Zn(2+) the enzyme activity was increased twofold. In the presence of .5 mM of Co(2+) and Mn(2+) the enzyme activity was increased fourfold. Mg(2+) is the ion that increases the enzyme activity the most. With .5 mM of Mg(2+) enzyme activity was increased sixfold. Inhibitors of this enzyme include diethylprocarbonate, Fe(2+), Hg(2+), and Mg(2+) (above 1mM). The maximum specific enzymatic activity is 3.2 micromol/min/mg. The optimum pH is 7.5. The maximum pH is 8. The optimum temperature is 30 degrees Celsius and the maximum temperature is 40 degrees Celsius. The molecular weight of o-succinylbenzoate CoA ligase is 185000 Da or 185 kDa. This enzyme is a tetramer, meaning it has four subunits in its quaternary structure. The PDB accession code i
3ipl
This is the crystal structure for o-succinylbenzoate CoA ligase in ''

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'' (strain N315) because the structure for ''

E. coli ''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus ''Escher ...

'' has not been crystallized as of yet.

Pathway

The pathway o-succinylbenzoate CoA ligase belongs to is called 1, 4-dihydroxy-2-napthoate biosynthesis I. Other organisms that contain this pathway are eukaryotic bacteria such as ''

Bacillus anthracis ''Bacillus anthracis'' is a gram-positive and rod-shaped bacterium that causes anthrax, a deadly disease to livestock and, occasionally, to humans. It is the only permanent ( obligate) pathogen within the genus ''Bacillus''. Its infection is a ...

''. Organisms that contain a pathway similar to this include ''

Arabidopsis thaliana ''Arabidopsis thaliana'', the thale cress, mouse-ear cress or arabidopsis, is a small flowering plant native to Eurasia and Africa. ''A. thaliana'' is considered a weed; it is found along the shoulders of roads and in disturbed land. A winter a ...

'' (gene AAE14), ''

Mycobacterium phlei ''Mycobacterium phlei'' is a species of acid-fast bacteria in the genus '' Mycobacterium''. It is characterized as one of the fast-growing mycobacteria. ''M. phlei'' has only occasionally been isolated in human infections, and patients infecte ...

'', and '' Synechocystis sp.'' (gene PCC 6803). The reason for the difference in pathways is due to the varying functions of Vitamin K. Eukaryotic bacteria use vitamin K II while other organisms use vitamin K I. Other pathways that include o-succinylbenzoate CoA ligase include 1, 4-diydroxy-2-naphthoate biosynthesis II (i.e. in Arabidopsis thaliana), biosynthesis of secondary metabolites, metabolic pathways, ubiquinone, and other terpenoid-quinone biosynthesis. In Bacillus anthracis this enzyme is a target of potential antibiotic discovery.

Reaction

The reaction in vitamin K synthesis that includes MenE is as follows: O-succinylbenzoate-CoA ligase illustration

ATP + 2-succinylbenzoate + CoA = AMP + diphosphate + 4-(2-carboxyphenyl)-4-oxobutanoyl-CoA The substrates of this reaction are

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CoA Coa may refer to: Places * Coa, County Fermanagh, a rural community in County Fermanagh, Northern Ireland * Côa River, a tributary of the Douro, Portugal ** Battle of Coa, part of the Peninsular War period of the Napoleonic Wars ** Côa Vall ...

, and 2-succinylbenzoate. The cofactors are ATP and CoA. The products are AMP, diphosphate, and 4-(2-carboxyphenyl)-4-oxobutanoyl-CoA.

References

{{DEFAULTSORT:O-succinylbenzoate-CoA ligase Vitamin K EC 6.2.1