1CXY

STRUCTURE AND CHARACTERIZATION OF ECTOTHIORHODOSPIRA VACUOLATA CYTOCHROME B558, A PROKARYOTIC HOMOLOGUE OF CYTOCHROME B5

Summary for 1CXY

• Entry DOI: 10.2210/pdb1cxy/pdb
• Descriptor: CYTOCHROME B5, PROTOPORPHYRIN IX CONTAINING FE (3 entities in total)
• Functional Keywords: helix, beta-strand, electron transport
• Biological source: Ectothiorhodospira shaposhnikovii
• Total number of polymer chains: 1
• Total formula weight: 10722.77

Authors

Kostanjevecki, V.,Leys, D.,Van Driessche, G.,Meyer, T.E.,Cusanovich, M.A.,Fischer, U.,Guisez, Y.,Van Beeumen, J. (deposition date: 1999-08-31, release date: 1999-09-10, Last modification date: 2024-11-20)

Primary citation

Kostanjevecki, V.,Leys, D.,Van Driessche, G.,Meyer, T.E.,Cusanovich, M.A.,Fischer, U.,Guisez, Y.,Van Beeumen, J.
Structure and characterization of Ectothiorhodospira vacuolata cytochrome b(558), a prokaryotic homologue of cytochrome b(5).
J.Biol.Chem., 274:35614-35620, 1999

PubMed Abstract: A soluble cytochrome b(558) from the purple phototropic bacterium Ectothiorhodospira vacuolata was completely sequenced by a combination of automated Edman degradation and mass spectrometry. The protein, with a measured mass of 10,094.7 Da, contains 90 residues and binds a single protoheme. Unexpectedly, the sequence shows homology to eukaryotic cytochromes b(5). As no prokaryotic homologue had been reported so far, we developed a protocol for the expression, purification, and crystallization of recombinant cytochrome b(558). The structure was solved by molecular replacement to a resolution of 1.65 A. It shows that cytochrome b(558) is indeed the first bacterial cytochrome b(5) to be characterized and differs from its eukaryotic counterparts by the presence of a disulfide bridge and a four-residue insertion in front of the sixth ligand (histidine). Eukaryotes contain a variety of b(5) homologues, including soluble and membrane-bound multifunctional proteins as well as multidomain enzymes such as sulfite oxidase, fatty-acid desaturase, nitrate reductase, and lactate dehydrogenase. A search of the Mycobacterium tuberculosis genome showed that a previously unidentified gene encodes a fatty-acid desaturase with an N-terminal b(5) domain. Thus, it may provide another example of a bacterial b(5) homologue.

PubMed: 10585439
DOI: 10.1074/jbc.274.50.35614

Experimental method

X-RAY DIFFRACTION (1.65 Å)