Difference between revisions of "Part:BBa K1080004"

Revision as of 17:47, 16 October 2014

ChlM
Mg protoporphyrin IX S-adenosyl methionine O-methyl transferase - Magnesium-protoporphyrin O-methyltransferase (ChlM) [PMID: 12828371; 12489983; 4436384]; ChloroP 1.1 predicts cp location

Usage and Biology

ChlM is responsible for the methylation of magnesium protoporphyrin IX. It encodes the enzyme Mg-protoporphyrin IX methyltransferase, to facilitate a highly regulated process in catalyzing magnesium chelatase [http://www.ncbi.nlm.nih.gov/pubmed/17135235]. The main reaction catalyzed by ChlM is the transfer of the methyl group from S-adenosylmethionine to the carboxyl group of the C13 propionate side chain of magnesium protoporphyrin IX [http://www.ncbi.nlm.nih.gov/pubmed/25077963]. This reaction is one of the most important steps in chlorophyll biosynthesis from protoporphyrin IX.

Operon Usage

This gene has been used in an operon with other genes responsible for catalysing the biosynthesis pathway from Mg-protoporphyrin IX to Protochlorophyllide. CTH1, Plastocyanin, and YCF54 are involved in the oxidative cyclase pathway. ChlM methylates Mg-protoporphyrin IX, facilitating the highly-regulated catalysis of Mg-chelatase. CTH1 catalyses the conversion of Mg-protoporphyrin IX monomethyl into divinyl protochlorophyllide, interacting with YCF54 and Plastocyanin.
The insertion of magnesium is the key component of the chlorophyll biosynthesis pathway.
The plasmid is under the control of the lac promoter.

Structure

Figure 1: Crystal structure of ChlM from cyanobacteria Synechocystis sp. [http://www.ncbi.nlm.nih.gov/pubmed/25077963]

Sequence and Features

Amino Acid Sequence

MASEIAQTAD VGSLTFAVGG VGAVVGLGAL LVATDHQKRR SEQMKSFDGD EKEAVKDYFN
TAGFERWRKI YGETDEVNKV QLDIRTGHAQ TVDKVLRWVD EEGSVQGITV ADCGCGTGSL
AIQLALRGAA VSASDISAAM ASEAEQRYQQ AVAAGQGKAP KVAPKFEALD LESVKGKYDT
VTCLDVMIHY PQDKVDAMIT HLAGLSDRRL IISFAPKTLS YSILKRIGEL FPGPSKATRA
YLHREEDVEA ALKRAGFKVT KREMTATSFY FSRLLEAIRE

References and documentation are available. Please note the modified algorithm for extinction coefficient.

Number of amino acids: 280

Molecular weight: 30440.6

Theoretical pI: 6.25

Amino acid composition:
Ala (A) 36 12.9%
Arg (R) 17 6.1%
Asn (N) 2 0.7%
Asp (D) 18 6.4%
Cys (C) 3 1.1%
Gln (Q) 12 4.3%
Glu (E) 20 7.1%
Gly (G) 23 8.2%
His (H) 5 1.8%
Ile (I) 13 4.6%
Leu (L) 22 7.9%
Lys (K) 19 6.8%
Met (M) 6 2.1%
Phe (F) 10 3.6%
Pro (P) 6 2.1%
Ser (S) 18 6.4%
Thr (T) 17 6.1%
Trp (W) 2 0.7%
Tyr (Y) 8 2.9%
Val (V) 23 8.2%
Pyl (O) 0 0.0%
Sec (U) 0 0.0%

(B)   0	  0.0%
(Z)   0	  0.0%
(X)   0	  0.0%

Total number of negatively charged residues (Asp + Glu): 38 Total number of positively charged residues (Arg + Lys): 36

Atomic composition:

Carbon C 1340 Hydrogen H 2150 Nitrogen N 376 Oxygen O 414 Sulfur S 9

Formula: C1340H2150N376O414S9 Total number of atoms: 4289

Extinction coefficients:

Extinction coefficients are in units of M-1 cm-1, at 280 nm measured in water.

Ext. coefficient 23045 Abs 0.1% (=1 g/l) 0.757, assuming all pairs of Cys residues form cystines

Ext. coefficient 22920 Abs 0.1% (=1 g/l) 0.753, assuming all Cys residues are reduced

Estimated half-life:

The N-terminal of the sequence considered is M (Met).

The estimated half-life is:

                            30 hours (mammalian reticulocytes, in vitro).
                           >20 hours (yeast, in vivo).
                           >10 hours (Escherichia coli, in vivo).

Instability index:

The instability index (II) is computed to be 34.88 This classifies the protein as stable.

Aliphatic index: 85.43

Grand average of hydropathicity (GRAVY): -0.198

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Source

Chlamydomonas reinhardtii

References