TSRI's main web site PROMISE mirror at TSRI Metalloprotein DB site Created: 15 August 1997
Last modified: 22 June 1998

Chlorophyll proteins

 Chlorophylls (Chls) represent a group of tetrapyrrole pigments found in photosynthetic organisms that contain magnesium (Mg) as the centrally chelated metal and contain a fifth five­membered ring (iso­cyclic ring E) [1]. Chls found in photosynthetic bacteria are termed bacteriochlorophylls (BChl). The macrocycle saturation state may be that of a (completely unsaturated) porphyrin (Chl­c), dihydroporphyrin (Chl­a, Chl­b, BChl­c, BChl­d and BChl­e) or tetrahydroporphyrin (BChl­a, BChl­b and BChl­g). BChl­c, BChl­d and BChl­e may be presented by homologues which show a diversity of substituents at positions 4 and 5 and different chirality at position 2a [2]. All naturally occurring Chls except for Chl­c are found with the ring D propionate etherified to a long­chain alcohol such as phytol or farnesol; non­etherified Chl precursors are termed chlorophyllides. The corresponding tetrapyrrole pigments lacking coordinated metal are termed pheophytins (Ph) or bacteriopheophytins (BPh).

The biosynthetic/structural relationships of Chls may be presented schematically [1]:

Two functional classes of the Chl-protein complexes may be defined: antenna systems (light­harvesting complexes) and photosynthetic reaction centres. Chl proteins can also be classified by Mg coordination, by Chl type, and further by sequence similarity.

Biosynthesis and metabolism of chlorophylls in metabolic pathway databases

KEGG PUMA Boehringer
Mannheim
map		 SoyBase
MAP00860; Porphyrin and chlorophyll metabolism Heme and porphyrins;
Chlorophylls		 H5 I5 J5 K5 L5 Chlorophyll synthesis
H6 I6 J6 K6 L6
H7

Chlorophyll proteins by chlorophyll magnesium coordination

Chlorophyll magnesium coordination Axial Mg
ligand		 Protein class
Chlorophyll-N-epsilon-His image
Pentacoordinate
NepsilonHis
Chlorophyll-N-delta-His image
Pentacoordinate
NdeltaHis
Chlorophyll-Asp image
Pentacoordinate
OdeltaAsp
Chlorophyll-fMet image
Pentacoordinate
OformylfMet
Chlorophyll-Leu image
Pentacoordinate
OalphaLeu
Chlorophyll-H2O image
Pentacoordinate
H2O

Chlorophyll proteins by chlorophyll type [1-3]

Click a chlorophyll image to get larger picture

Chlorophyll type /
LIGAND entry		 R4/R5
variants		 Occurence Absorption
maxima (nm)
Chlorophyll a image

Chl­a (C05306)
-
  • Photosystem I of algae and higher plants
  • Photosystem II of algae and higher plants
660-725
Chlorophyll b image

Chl­b (C05307)
-
  • Photosystem I of algae and higher plants
  • Photosystem II of algae and higher plants
640-695
Chlorophyll c1 image

Chl­c1
-
  • Light­harvesting proteins in diatoms, dinoflagellates, brown macrophytic algae and cryptophytes
630-740
Chlorophyll c2 image

Chl­c2
-
  • Light­harvesting proteins in diatoms, dinoflagellates, brown macrophytic algae and cryptophytes
630-740
Bacteriochlorophyll a image

BChl­a
-
800-910
Bacteriochlorophyll b image

BChl­b
-
1020-1035
Bacteriochlorophyll c image

BChl­c
 R4 = -C2H5;
-C3H7;
-i­C4H9*;

R5 = -C2H5;
-CH3

  • Light­harvesting complexes of filamentous photosynthetic bacteria and green sulphur bacteria
745-760
Bacteriochlorophyll d image

BChl­d
 R4 = -C2H5;
-C3H7;
-i­C4H9*;
-neo­C5H11×

R5 = -C2H5;
-CH3

  • Light­harvesting complexes of green and brown sulphur bacteria
725-745
Bacteriochlorophyll e image

BChl­e
 R4 = -C2H5;
-C3H7;
-i­C4H9*
  • Light­harvesting complexes of green and brown sulphur bacteria
715-725
Bacteriochlorophyll g image

BChl­g
-
  • Photosynthetic proteins of Heliobacterium
788

* -i­C4H9 = -CH2CH(CH3)2;
× -neo­C5H11 = -CH2C(CH3)3

Chlorophyll proteins in motif databases

PRINTS ID PRINTS AC PROSITE/BLOCKS ID PROSITE AC BLOCKS AC
BCHLROPHYLLC PR00656
-
-
-
LIGHTHARVSTA PR00673 ANTENNA_COMP_ALPHA PS00968 BL00968
LIGHTHARVSTB PR00674 ANTENNA_COMP_BETA PS00969 BL00969
PHOTSYSPSAAB PR00257 PHOTOSYSTEM_I_PSAAB PS00419 BL00419
REACTNCENTRE PR00256 REACTION_CENTER PS00244 BL00244

Chlorophyll proteins in PROMISE

PROMISE ID Description
FMOC Fenna­Matthews­Olson complex (bacteriochlorophyll a protein)
LH2PB Light­harvesting complex II of purple bacteria
PRCPB Photosynthetic reaction centres of purple bacteria

HET groups in PDB (at BSM)

HET group Description Formula
BCL
Bacteriochlorophyll C55H74N4O6Mg2+
CLA
Chlorophyll a C55H72N4O5Mg2+

References

  1. Beale, S.I. and Weinstein, J.D. (1991) Biochemistry and regulation of photosynthetic pigment formation in plants and algae. In Jordan, P.M., Ed. Biosynthesis of Tetrapyrroles. Elsevier, Amsterdam, pp. 155-235.
  2. Smith, K.M. (1991) The structure and biosynthesis of bacteriochlorophylls. In Jordan, P.M., Ed. Biosynthesis of Tetrapyrroles. Elsevier, Amsterdam, pp. 237-255.
  3. Pierson, B.K. and Olson, J.M. (1987) Photosynthetic bacteria. In Amesz, J., Ed. Photosynthesis. Elsevier, Amsterdam, pp. 21-42.
General references on chlorophyll proteins