Bacterial antenna complex

Pfam_box
Symbol = LHC
Name = Antenna complex alpha/beta subunit


width =
caption =
Pfam= PF00556
InterPro= IPR000066
SMART=
PROSITE = PDOC00748
SCOP = 1lgh
TCDB =
OPM family= 1
OPM protein= 1lgh
PDB=PDB3|1lghK:11-45 PDB3|1nkzD:5-41 PDB3|1kzuB:5-41PDB3|1ijdF:6-42 PDB3|1nw0A:1-42 PDB3|1xrdA:1-42

Bacterial antenna complex proteins are main components light-harvesting complexes in photosynthetic bacteria. [ The crystal structure of the light-harvesting complex II (B800-850) from Rhodospirillum molischianum. Koepke J, Hu X, Muenke C, Schulten K, Michel H; Structure 1996;4:581-597. PMID|8736556 ]

In photosynthetic bacteria the antenna complexes function as light-harvesting systems that absorb light radiation and transfer the excitation energy to the reaction centres. The antenna complexes are generally composed of two types of polypeptides (alpha and beta chains); two or three types of bacteriochlorophyll (BChl) molecules and some carotenoidscite journal |author=Wagner-Huber R, Brunisholz RA, Bissig I, Frank G, Suter F, Zuber H |title=The primary structure ofthe antenna polypeptides of Ectothiorhodospira halochloris and Ectothiorhodospira halophila. Four core-type antenna polypeptides in E. halochloris and E. halophila |journal=Eur. J. Biochem. |volume=205 |issue=3 |pages=917–925 |year=1992 |pmid=1577009 |doi=10.1111/j.1432-1033.1992.tb16858.x] cite journal |author=Brunisholz RA, Zuber H |title=Structure, function and organization of antenna polypeptides and antenna complexes from the three families of Rhodospirillaneae |journal=J. Photochem. Photobiol. B |volume=15 |issue=1 |pages=113–140 |year=1992 |pmid=1460542 |doi=10.1016/1011-1344(92)87010-7] . Both the alpha and the beta chains of antenna complexes are small proteins of 42 to 68 residues which share a three-domain organization. They are composed of a N-terminal hydrophilic cytoplasmic domain followed by a transmembrane region and a C-terminal hydrophilic periplasmic domain. In the transmembrane region of both chains there is a conserved histidine which is most probably involvedin the binding of the magnesium atom of a bacteriochlorophyll group. The beta chains contain an additional conserved histidine which is located at the C-terminal extremity of the cytoplasmic domain and which is also thought to be involved in bacteriochlorophyll-binding.

ubfamilies

*Antenna complex, alpha subunit InterPro|IPR002361
*Antenna complex, beta subunit InterPro|IPR002362

References