Sandbox Reserved 325
From Proteopedia
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166 redidue mature CM forms all alpha helix strruc | 166 redidue mature CM forms all alpha helix strruc | ||
10 aplha helix | 10 aplha helix | ||
| + | 86% of residues in alpha helicies | ||
| + | 1 S-S bond between Cys 160 and cys 193 | ||
| + | ph tolerance from 4.0 to 7.5 for optimal activity | ||
| + | active site exists though hydrogen bonding and electrostatic interactions with chorismate | ||
| Line 32: | Line 36: | ||
may be involved in pathogenesis. | may be involved in pathogenesis. | ||
one can take advantage of non-occurance of CMs in humans to try to develop antimicrobial drugs for human pathogens such as tb | one can take advantage of non-occurance of CMs in humans to try to develop antimicrobial drugs for human pathogens such as tb | ||
| + | no func in non-shik pathways like those of macrophages of mammals. target this for TB infection | ||
| + | ph is 4.5 om tb macrophage enviro. acidic. | ||
==References== | ==References== | ||
<references/> | <references/> | ||
Revision as of 01:01, 3 April 2011
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| 2f6l, resolution 1.70Å () | |||||||||
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| Gene: | Rv1885c (Mycobacterium tuberculosis) | ||||||||
| Activity: | Chorismate mutase, with EC number 5.4.99.5 | ||||||||
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| Resources: | FirstGlance, OCA, RCSB, PDBsum | ||||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||||
| This Sandbox is Reserved from January 10, 2010, through April 10, 2011 for use in BCMB 307-Proteins course taught by Andrea Gorrell at the University of Northern British Columbia, Prince George, BC, Canada. |
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Contents |
Chorismate Mutase
Introduction
The gene Rv1885c from Mycobacteriam tuberculosis encodes for a non-functional chorismate mutase (*MtCM)[1]. This non-functional mutase has a 33-amino-acid cleavable sequence [1]. It is a vital enzyme in the shikimate pathway, which allows for the synthesis of tryptophan, tyrosinem and phenylalanine [1]. Chorismate mutase provides a 2x106 fold increase in the rate of reacrion in comparision to the uncatalyzed reaction [2]. Chorismate mutase only occurs in bacteria, higher plants, and fungi, due to the fact that the shikimate pathway is only found in these organisms [3]. In Escherichia coli, chorismate mutase has a periplasmic destination[1]. In M. tuberculosis there is in abscence of a periplasmic compartment for chorismate mutase, so it secretes into the culture filtrate of M. tuberculosis[1]. It is believed that a pseudoperiplasmic space might exist in M. tuberculosis[1]. Rv1885c is synthesized along with the 33-amino-acid terminal sequence, which when expressed with Escherichia coli, is cleaved off the mature protein[1]. Chorismate mutase is the only example of an enzyme catalyzing a percyclic reaction [3]
Structure
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has dimeric state in concentrations as low as 5nM has an all alpha helical structure active site forms in single chain without help from second half of dimer active site is critical for catalysis. it is made up of Arg 49, Lys 60, Arg 72, Thr 105, Glu 109, and Arg 134 not regulated by aromatic amino acids, which is supported by the fact that there are no allosteric regulatory sites.
alpha helicalstruc similar to e coli CM and S. cerevisae CM
quaternary structure determined by molecular sieve chromatography MW 36,00 Da based on monomeric mass of 18,474 Da clearly shows it is dimeric All naturally occuring CMS function as dimers or trimers works best at 37 deg C ph 7.5 166 redidue mature CM forms all alpha helix strruc 10 aplha helix 86% of residues in alpha helicies 1 S-S bond between Cys 160 and cys 193 ph tolerance from 4.0 to 7.5 for optimal activity active site exists though hydrogen bonding and electrostatic interactions with chorismate
here is a
Mechanism
in michaelis menten kinetics it has Km of 0.5 ± 0.05 mM and Kcat of 60 s-1 Chorismate mutase is an essential enzyme in the shikimate pathway [1]. This pathway allows for the biosynthesis of aromatic amino acids tryptophan, tyrosine, and phenylalanine [1]. The production of tyrosine and phenylalanine is achieved by what is called a Claisen arrangement. first converting chorismate to prephenate. Prephenate then reacts with prephenate dehydratase and prephenate dehydrogenase which forms phenylpyruvate and hydroxyphenylpyruvate. After this occursm aminotransferase converts hydroxy-phenylpyruvate and phenylpyruvate to phenylalanine and tyrosine. Chorismate mutase provides a 2x106 fold increase in the rate of reaction, in comparison to the uncatalyzed reaction [4]. It is the only example of an enzyme catalyzing a percyclic reaction [3]
Chorismate Mutase and Tuberculosis
may be involved in pathogenesis. one can take advantage of non-occurance of CMs in humans to try to develop antimicrobial drugs for human pathogens such as tb no func in non-shik pathways like those of macrophages of mammals. target this for TB infection ph is 4.5 om tb macrophage enviro. acidic.
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 Kim SK, Reddy SK, Nelson BC, Vasquez GB, Davis A, Howard AJ, Patterson S, Gilliland GL, Ladner JE, Reddy PT. Biochemical and structural characterization of the secreted chorismate mutase (Rv1885c) from Mycobacterium tuberculosis H37Rv: an *AroQ enzyme not regulated by the aromatic amino acids. J Bacteriol. 2006 Dec;188(24):8638-48. PMID:17146044 doi:188/24/8638
- ↑ P.D. Lyne, A.J. Mulholland, W.G. Richards. Insights into chorismate mutase catalysis from a combined qm/mm simulation of the enzyme reaction. Journal of the American Chemistry Society. 1995 117(45):11345-11350
- ↑ 3.0 3.1 3.2 Kast P, Grisostomi C, Chen IA, Li S, Krengel U, Xue Y, Hilvert D. A strategically positioned cation is crucial for efficient catalysis by chorismate mutase. J Biol Chem. 2000 Nov 24;275(47):36832-8. PMID:10960481 doi:10.1074/jbc.M006351200
- ↑ P.D. Lyne, A.J. Mulholland, W.G. Richards. Insights into chorismate mutase catalysis from a combined qm/mm simulation of the enzyme reaction. Journal of the American Chemistry Society. 1995 117(45):11345-11350
